21387219 has 8 divisors (see below), whose sum is σ = 32590080. Its totient is φ = 12221256.

The previous prime is 21387203. The next prime is 21387227. The reversal of 21387219 is 91278312.

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

It is not a de Polignac number, because 21387219 - 2⁴ = 21387203 is a prime.

It is a super-2 number, since 2×21387219² = 914826273107922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21387219.

It is not an unprimeable number, because it can be changed into a prime (21387299) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 509199 + ... + 509240.

It is an arithmetic number, because the mean of its divisors is an integer number (4073760).

Almost surely, 2^21387219 is an apocalyptic number.

21387219 is a deficient number, since it is larger than the sum of its proper divisors (11202861).

21387219 is a wasteful number, since it uses less digits than its factorization.

21387219 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1018449.

The product of its digits is 6048, while the sum is 33.

The square root of 21387219 is about 4624.6317691250. The cubic root of 21387219 is about 277.5778273711.

The spelling of 21387219 in words is "twenty-one million, three hundred eighty-seven thousand, two hundred nineteen".