21518952 has 128 divisors (see below), whose sum is σ = 67737600. Its totient is φ = 5545728.

The previous prime is 21518947. The next prime is 21518969. The reversal of 21518952 is 25981512.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 128773 + ... + 128939.

It is an arithmetic number, because the mean of its divisors is an integer number (529200).

Almost surely, 2^21518952 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 21518952, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33868800).

21518952 is an abundant number, since it is smaller than the sum of its proper divisors (46218648).

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

21518952 is a wasteful number, since it uses less digits than its factorization.

21518952 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255 (or 251 counting only the distinct ones).

The product of its digits is 7200, while the sum is 33.

The square root of 21518952 is about 4638.8524443013. The cubic root of 21518952 is about 278.1465679861.

The spelling of 21518952 in words is "twenty-one million, five hundred eighteen thousand, nine hundred fifty-two".