21329864 has 16 divisors (see below), whose sum is σ = 40049100. Its totient is φ = 10650112.

The previous prime is 21329851. The next prime is 21329879. The reversal of 21329864 is 46892312.

It can be written as a sum of positive squares in 2 ways, for example, as 15288100 + 6041764 = 3910^2 + 2458^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6452 + ... + 9180.

Almost surely, 2^21329864 is an apocalyptic number.

It is an amenable number.

21329864 is a deficient number, since it is larger than the sum of its proper divisors (18719236).

21329864 is a wasteful number, since it uses less digits than its factorization.

21329864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3712 (or 3708 counting only the distinct ones).

The product of its digits is 20736, while the sum is 35.

The square root of 21329864 is about 4618.4265718965. The cubic root of 21329864 is about 277.3294745416.

The spelling of 21329864 in words is "twenty-one million, three hundred twenty-nine thousand, eight hundred sixty-four".