21870519 has 8 divisors (see below), whose sum is σ = 31811712. Its totient is φ = 13254840.

The previous prime is 21870473. The next prime is 21870547. The reversal of 21870519 is 91507812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21870519 - 2¹¹ = 21868471 is a prime.

It is a super-2 number, since 2×21870519² = 956639202658722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 662743 = 21870519 / (2 + 1 + 8 + 7 + 0 + 5 + 1 + 9).

It is a plaindrome in base 8.

It is a self number, because there is not a number n which added to its sum of digits gives 21870519.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21870559) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 331339 + ... + 331404.

It is an arithmetic number, because the mean of its divisors is an integer number (3976464).

Almost surely, 2^21870519 is an apocalyptic number.

21870519 is a deficient number, since it is larger than the sum of its proper divisors (9941193).

21870519 is a wasteful number, since it uses less digits than its factorization.

21870519 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 662757.

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 21870519 is about 4676.5926698826. The cubic root of 21870519 is about 279.6531376633.

Multiplying 21870519 by its sum of digits (33), we get a palindrome (721727127).

It can be divided in two parts, 21 and 870519, that added together give a triangular number (870540 = T₁₃₁₉).

The spelling of 21870519 in words is "twenty-one million, eight hundred seventy thousand, five hundred nineteen".