21940656 has 20 divisors (see below), whose sum is σ = 56680152. Its totient is φ = 7313536.

The previous prime is 21940651. The next prime is 21940657. The reversal of 21940656 is 65604912.

It is not an unprimeable number, because it can be changed into a prime (21940651) 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, 228501 + ... + 228596.

Almost surely, 2^21940656 is an apocalyptic number.

It is an amenable number.

21940656 is an abundant number, since it is smaller than the sum of its proper divisors (34739496).

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

21940656 is a wasteful number, since it uses less digits than its factorization.

21940656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 457108 (or 457102 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 33.

The square root of 21940656 is about 4684.0853963180. The cubic root of 21940656 is about 279.9517603970.

The spelling of 21940656 in words is "twenty-one million, nine hundred forty thousand, six hundred fifty-six".