21610657 has 4 divisors (see below), whose sum is σ = 22748080. Its totient is φ = 20473236.

The previous prime is 21610643. The next prime is 21610661. The reversal of 21610657 is 75601612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21610657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21610607) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 568683 + ... + 568720.

It is an arithmetic number, because the mean of its divisors is an integer number (5687020).

Almost surely, 2^21610657 is an apocalyptic number.

It is an amenable number.

21610657 is a deficient number, since it is larger than the sum of its proper divisors (1137423).

21610657 is a wasteful number, since it uses less digits than its factorization.

21610657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1137422.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21610657 is about 4648.7263847209. The cubic root of 21610657 is about 278.5411237939.

The spelling of 21610657 in words is "twenty-one million, six hundred ten thousand, six hundred fifty-seven".