21399712 has 12 divisors (see below), whose sum is σ = 42130746. Its totient is φ = 10699840.

The previous prime is 21399701. The next prime is 21399737. The reversal of 21399712 is 21799312.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 18696976 + 2702736 = 4324^2 + 1644^2 .

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334339 + ... + 334402.

Almost surely, 2^21399712 is an apocalyptic number.

It is an amenable number.

21399712 is a deficient number, since it is larger than the sum of its proper divisors (20731034).

21399712 is an equidigital number, since it uses as much as digits as its factorization.

21399712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 668751 (or 668743 counting only the distinct ones).

The product of its digits is 6804, while the sum is 34.

The square root of 21399712 is about 4625.9822740689. The cubic root of 21399712 is about 277.6318643920.

The spelling of 21399712 in words is "twenty-one million, three hundred ninety-nine thousand, seven hundred twelve".