21255572 has 24 divisors (see below), whose sum is σ = 40721352. Its totient is φ = 9648000.

The previous prime is 21255569. The next prime is 21255581. The reversal of 21255572 is 27555212.

It can be written as a sum of positive squares in 4 ways, for example, as 498436 + 20757136 = 706^2 + 4556^2 .

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 179 + ... + 6522.

It is an arithmetic number, because the mean of its divisors is an integer number (1696723).

Almost surely, 2^21255572 is an apocalyptic number.

It is an amenable number.

21255572 is a deficient number, since it is larger than the sum of its proper divisors (19465780).

21255572 is a wasteful number, since it uses less digits than its factorization.

21255572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6779 (or 6777 counting only the distinct ones).

The product of its digits is 7000, while the sum is 29.

The square root of 21255572 is about 4610.3765572890. The cubic root of 21255572 is about 277.0071201148.

The spelling of 21255572 in words is "twenty-one million, two hundred fifty-five thousand, five hundred seventy-two".