21985256 has 8 divisors (see below), whose sum is σ = 41222370. Its totient is φ = 10992624.

The previous prime is 21985253. The next prime is 21985259. The reversal of 21985256 is 65258912.

It is an interprime number because it is at equal distance from previous prime (21985253) and next prime (21985259).

It can be written as a sum of positive squares in only one way, i.e., 16273156 + 5712100 = 4034^2 + 2390^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (21985253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1374071 + ... + 1374086.

Almost surely, 2^21985256 is an apocalyptic number.

It is an amenable number.

21985256 is a deficient number, since it is larger than the sum of its proper divisors (19237114).

21985256 is a wasteful number, since it uses less digits than its factorization.

21985256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2748163 (or 2748159 counting only the distinct ones).

The product of its digits is 43200, while the sum is 38.

The square root of 21985256 is about 4688.8437807204. The cubic root of 21985256 is about 280.1413232164.

The spelling of 21985256 in words is "twenty-one million, nine hundred eighty-five thousand, two hundred fifty-six".