21356744 has 16 divisors (see below), whose sum is σ = 40100400. Its totient is φ = 10663312.

The previous prime is 21356723. The next prime is 21356759. The reversal of 21356744 is 44765312.

It is a super-2 number, since 2×21356744² = 912221028563072, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21356744.

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, 6167 + ... + 8985.

It is an arithmetic number, because the mean of its divisors is an integer number (2506275).

Almost surely, 2^21356744 is an apocalyptic number.

It is an amenable number.

21356744 is a deficient number, since it is larger than the sum of its proper divisors (18743656).

21356744 is a wasteful number, since it uses less digits than its factorization.

21356744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3772 (or 3768 counting only the distinct ones).

The product of its digits is 20160, while the sum is 32.

The square root of 21356744 is about 4621.3357376412. The cubic root of 21356744 is about 277.4459229636.

The spelling of 21356744 in words is "twenty-one million, three hundred fifty-six thousand, seven hundred forty-four".