21331738 has 12 divisors (see below), whose sum is σ = 32426730. Its totient is φ = 10524696.

The previous prime is 21331729. The next prime is 21331777. The reversal of 21331738 is 83713312.

It can be written as a sum of positive squares in only one way, i.e., 20277009 + 1054729 = 4503^2 + 1027^2 .

It is a super-2 number, since 2×21331738² = 910086092201288, which contains 22 as substring.

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, 11628 + ... + 13336.

Almost surely, 2^21331738 is an apocalyptic number.

21331738 is a deficient number, since it is larger than the sum of its proper divisors (11094992).

21331738 is an equidigital number, since it uses as much as digits as its factorization.

21331738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1869 (or 1790 counting only the distinct ones).

The product of its digits is 3024, while the sum is 28.

The square root of 21331738 is about 4618.6294503889. The cubic root of 21331738 is about 277.3375961782.

The spelling of 21331738 in words is "twenty-one million, three hundred thirty-one thousand, seven hundred thirty-eight".