21664410 has 16 divisors (see below), whose sum is σ = 51994656. Its totient is φ = 5777168.

The previous prime is 21664373. The next prime is 21664417. The reversal of 21664410 is 1446612.

It is not an unprimeable number, because it can be changed into a prime (21664417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 361044 + ... + 361103.

It is an arithmetic number, because the mean of its divisors is an integer number (3249666).

Almost surely, 2^21664410 is an apocalyptic number.

21664410 is an abundant number, since it is smaller than the sum of its proper divisors (30330246).

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

21664410 is a wasteful number, since it uses less digits than its factorization.

21664410 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 722157.

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 21664410 is about 4654.5042700593. The cubic root of 21664410 is about 278.7718745192.

The spelling of 21664410 in words is "twenty-one million, six hundred sixty-four thousand, four hundred ten".