21025916 has 12 divisors (see below), whose sum is σ = 37790088. Its totient is φ = 10228752.

The previous prime is 21025909. The next prime is 21025937. The reversal of 21025916 is 61952012.

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, 70886 + ... + 71181.

It is an arithmetic number, because the mean of its divisors is an integer number (3149174).

Almost surely, 2^21025916 is an apocalyptic number.

It is an amenable number.

21025916 is a deficient number, since it is larger than the sum of its proper divisors (16764172).

21025916 is a wasteful number, since it uses less digits than its factorization.

21025916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142108 (or 142106 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 21025916 is about 4585.4024905127. The cubic root of 21025916 is about 276.0058634895.

Adding to 21025916 its reverse (61952012), we get a palindrome (82977928).

The spelling of 21025916 in words is "twenty-one million, twenty-five thousand, nine hundred sixteen".