21970656 has 96 divisors (see below), whose sum is σ = 65318400. Its totient is φ = 7182720.

The previous prime is 21970609. The next prime is 21970691. The reversal of 21970656 is 65607912.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21970656.

It is a congruent number.

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, 50761 + ... + 51191.

It is an arithmetic number, because the mean of its divisors is an integer number (680400).

Almost surely, 2^21970656 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 21970656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32659200).

21970656 is an abundant number, since it is smaller than the sum of its proper divisors (43347744).

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

21970656 is a wasteful number, since it uses less digits than its factorization.

21970656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 509 (or 495 counting only the distinct ones).

The product of its (nonzero) digits is 22680, while the sum is 36.

The square root of 21970656 is about 4687.2866351440. The cubic root of 21970656 is about 280.0792972684.

The spelling of 21970656 in words is "twenty-one million, nine hundred seventy thousand, six hundred fifty-six".