21208419 has 32 divisors (see below), whose sum is σ = 32537600. Its totient is φ = 13646880.

The previous prime is 21208399. The next prime is 21208423. The reversal of 21208419 is 91480212.

It is not a de Polignac number, because 21208419 - 2⁵ = 21208387 is a prime.

It is a super-2 number, since 2×21208419² = 899594072959122, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21208392 and 21208401.

It is not an unprimeable number, because it can be changed into a prime (21208819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 130032 + ... + 130194.

It is an arithmetic number, because the mean of its divisors is an integer number (1016800).

Almost surely, 2^21208419 is an apocalyptic number.

21208419 is a deficient number, since it is larger than the sum of its proper divisors (11329181).

21208419 is a wasteful number, since it uses less digits than its factorization.

21208419 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 312 (or 306 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 21208419 is about 4605.2599275177. The cubic root of 21208419 is about 276.8021324958.

The spelling of 21208419 in words is "twenty-one million, two hundred eight thousand, four hundred nineteen".