21320964 has 144 divisors (see below), whose sum is σ = 66801280. Its totient is φ = 5598720.

The previous prime is 21320947. The next prime is 21320969. The reversal of 21320964 is 46902312.

It is a super-4 number, since 4×21320964⁴ (a number of 30 digits) contains 4444 as substring.

It is not an unprimeable number, because it can be changed into a prime (21320969) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 292032 + ... + 292104.

Almost surely, 2^21320964 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21320964, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33400640).

21320964 is an abundant number, since it is smaller than the sum of its proper divisors (45480316).

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

21320964 is a wasteful number, since it uses less digits than its factorization.

21320964 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170 (or 165 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 21320964 is about 4617.4629397538. The cubic root of 21320964 is about 277.2908967726.

The spelling of 21320964 in words is "twenty-one million, three hundred twenty thousand, nine hundred sixty-four".