21481868 has 12 divisors (see below), whose sum is σ = 38510472. Its totient is φ = 10478880.

The previous prime is 21481861. The next prime is 21481871. The reversal of 21481868 is 86818412.

It is a super-2 number, since 2×21481868² = 922941305538848, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21481861) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65330 + ... + 65657.

It is an arithmetic number, because the mean of its divisors is an integer number (3209206).

Almost surely, 2^21481868 is an apocalyptic number.

It is an amenable number.

21481868 is a deficient number, since it is larger than the sum of its proper divisors (17028604).

21481868 is a wasteful number, since it uses less digits than its factorization.

21481868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 131032 (or 131030 counting only the distinct ones).

The product of its digits is 24576, while the sum is 38.

The square root of 21481868 is about 4634.8536114963. The cubic root of 21481868 is about 277.9866977746.

The spelling of 21481868 in words is "twenty-one million, four hundred eighty-one thousand, eight hundred sixty-eight".