21451968 has 42 divisors (see below), whose sum is σ = 61489844. Its totient is φ = 7150464.

The previous prime is 21451957. The next prime is 21451973. The reversal of 21451968 is 86915412.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 18046 + ... + 19197.

Almost surely, 2^21451968 is an apocalyptic number.

It is an amenable number.

21451968 is an abundant number, since it is smaller than the sum of its proper divisors (40037876).

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

21451968 is a wasteful number, since it uses less digits than its factorization.

21451968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37261 (or 37248 counting only the distinct ones).

The product of its digits is 17280, while the sum is 36.

The square root of 21451968 is about 4631.6269279811. The cubic root of 21451968 is about 277.8576639685.

The spelling of 21451968 in words is "twenty-one million, four hundred fifty-one thousand, nine hundred sixty-eight".