21239516 has 12 divisors (see below), whose sum is σ = 37258032. Its totient is φ = 10594368.

The previous prime is 21239507. The next prime is 21239551. The reversal of 21239516 is 61593212.

It is a super-2 number, since 2×21239516² = 902234079828512, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4400 + ... + 7863.

It is an arithmetic number, because the mean of its divisors is an integer number (3104836).

Almost surely, 2^21239516 is an apocalyptic number.

It is an amenable number.

21239516 is a deficient number, since it is larger than the sum of its proper divisors (16018516).

21239516 is a wasteful number, since it uses less digits than its factorization.

21239516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12700 (or 12698 counting only the distinct ones).

The product of its digits is 3240, while the sum is 29.

The square root of 21239516 is about 4608.6349388946. The cubic root of 21239516 is about 276.9373541468.

The spelling of 21239516 in words is "twenty-one million, two hundred thirty-nine thousand, five hundred sixteen".