21181952 has 40 divisors (see below), whose sum is σ = 46182312. Its totient is φ = 9625600.

The previous prime is 21181933. The next prime is 21181961. The reversal of 21181952 is 25918112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3752 + ... + 7512.

Almost surely, 2^21181952 is an apocalyptic number.

21181952 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21181952, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23091156).

21181952 is an abundant number, since it is smaller than the sum of its proper divisors (25000360).

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

21181952 is an equidigital number, since it uses as much as digits as its factorization.

21181952 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3790 (or 3774 counting only the distinct ones).

The product of its digits is 1440, while the sum is 29.

The square root of 21181952 is about 4602.3854684283. The cubic root of 21181952 is about 276.6869396928.

The spelling of 21181952 in words is "twenty-one million, one hundred eighty-one thousand, nine hundred fifty-two".