21388252 has 24 divisors (see below), whose sum is σ = 39223296. Its totient is φ = 10185648.

The previous prime is 21388249. The next prime is 21388271. The reversal of 21388252 is 25288312.

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, 34933 + ... + 35539.

It is an arithmetic number, because the mean of its divisors is an integer number (1634304).

Almost surely, 2^21388252 is an apocalyptic number.

It is an amenable number.

21388252 is a deficient number, since it is larger than the sum of its proper divisors (17835044).

21388252 is a wasteful number, since it uses less digits than its factorization.

21388252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1017 (or 1015 counting only the distinct ones).

The product of its digits is 7680, while the sum is 31.

The square root of 21388252 is about 4624.7434523441. The cubic root of 21388252 is about 277.5822962906.

The spelling of 21388252 in words is "twenty-one million, three hundred eighty-eight thousand, two hundred fifty-two".