21255372 has 90 divisors (see below), whose sum is σ = 59286612. Its totient is φ = 6638976.

The previous prime is 21255361. The next prime is 21255383. The reversal of 21255372 is 27355212.

21255372 is a `hidden beast` number, since 2 + 125 + 537 + 2 = 666.

It is an interprime number because it is at equal distance from previous prime (21255361) and next prime (21255383).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 93523 + ... + 93749.

Almost surely, 2^21255372 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 21255372, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29643306).

21255372 is an abundant number, since it is smaller than the sum of its proper divisors (38031240).

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

21255372 is a wasteful number, since it uses less digits than its factorization.

21255372 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277 (or 249 counting only the distinct ones).

The product of its digits is 4200, while the sum is 27.

The square root of 21255372 is about 4610.3548670357. The cubic root of 21255372 is about 277.0062512980.

The spelling of 21255372 in words is "twenty-one million, two hundred fifty-five thousand, three hundred seventy-two".