20657256 has 64 divisors (see below), whose sum is σ = 55080000. Its totient is φ = 6437376.

The previous prime is 20657233. The next prime is 20657269. The reversal of 20657256 is 65275602.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40330 + ... + 40838.

It is an arithmetic number, because the mean of its divisors is an integer number (860625).

Almost surely, 2^20657256 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20657256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27540000).

20657256 is an abundant number, since it is smaller than the sum of its proper divisors (34422744).

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

20657256 is a wasteful number, since it uses less digits than its factorization.

20657256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 626 (or 622 counting only the distinct ones).

The product of its (nonzero) digits is 25200, while the sum is 33.

The square root of 20657256 is about 4545.0254124702. The cubic root of 20657256 is about 274.3832171338.

The spelling of 20657256 in words is "twenty million, six hundred fifty-seven thousand, two hundred fifty-six".