21251288 has 32 divisors (see below), whose sum is σ = 41131200. Its totient is φ = 10287648.

The previous prime is 21251281. The next prime is 21251299. The reversal of 21251288 is 88215212.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21251288.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251281) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 55883 + ... + 56261.

It is an arithmetic number, because the mean of its divisors is an integer number (1285350).

Almost surely, 2^21251288 is an apocalyptic number.

It is an amenable number.

21251288 is a deficient number, since it is larger than the sum of its proper divisors (19879912).

21251288 is a wasteful number, since it uses less digits than its factorization.

21251288 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 591 (or 587 counting only the distinct ones).

The product of its digits is 2560, while the sum is 29.

The square root of 21251288 is about 4609.9119297444. The cubic root of 21251288 is about 276.9885088657.

The spelling of 21251288 in words is "twenty-one million, two hundred fifty-one thousand, two hundred eighty-eight".