21306744 has 48 divisors (see below), whose sum is σ = 57918120. Its totient is φ = 7076160.

The previous prime is 21306743. The next prime is 21306749. The reversal of 21306744 is 44760312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21306743) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 38679 + ... + 39225.

Almost surely, 2^21306744 is an apocalyptic number.

21306744 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21306744 is an abundant number, since it is smaller than the sum of its proper divisors (36611376).

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

21306744 is a wasteful number, since it uses less digits than its factorization.

21306744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1100 (or 1093 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 27.

The square root of 21306744 is about 4615.9228763055. The cubic root of 21306744 is about 277.2292367481.

The spelling of 21306744 in words is "twenty-one million, three hundred six thousand, seven hundred forty-four".