21608757 has 24 divisors (see below), whose sum is σ = 33190560. Its totient is φ = 13508640.

The previous prime is 21608749. The next prime is 21608759. The reversal of 21608757 is 75780612.

It is not a de Polignac number, because 21608757 - 2³ = 21608749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21608759) 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 23 ways as a sum of consecutive naturals, for example, 17707 + ... + 18887.

It is an arithmetic number, because the mean of its divisors is an integer number (1382940).

Almost surely, 2^21608757 is an apocalyptic number.

It is an amenable number.

21608757 is a deficient number, since it is larger than the sum of its proper divisors (11581803).

21608757 is a wasteful number, since it uses less digits than its factorization.

21608757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1313 (or 1310 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 36.

The square root of 21608757 is about 4648.5220231811. The cubic root of 21608757 is about 278.5329604813.

The spelling of 21608757 in words is "twenty-one million, six hundred eight thousand, seven hundred fifty-seven".