21265616 has 20 divisors (see below), whose sum is σ = 42994272. Its totient is φ = 10170336.

The previous prime is 21265603. The next prime is 21265619. The reversal of 21265616 is 61656212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21265619) by changing a digit.

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, 28526 + ... + 29261.

Almost surely, 2^21265616 is an apocalyptic number.

It is an amenable number.

21265616 is an abundant number, since it is smaller than the sum of its proper divisors (21728656).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21265616 is a wasteful number, since it uses less digits than its factorization.

21265616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57818 (or 57812 counting only the distinct ones).

The product of its digits is 4320, while the sum is 29.

The square root of 21265616 is about 4611.4657105957. The cubic root of 21265616 is about 277.0507450898.

The spelling of 21265616 in words is "twenty-one million, two hundred sixty-five thousand, six hundred sixteen".