21964572 has 72 divisors (see below), whose sum is σ = 64960896. Its totient is φ = 6126624.

The previous prime is 21964567. The next prime is 21964573. The reversal of 21964572 is 27546912.

21964572 is a `hidden beast` number, since 2 + 1 + 9 + 645 + 7 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21964573) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 9823 + ... + 11849.

Almost surely, 2^21964572 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 21964572, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32480448).

21964572 is an abundant number, since it is smaller than the sum of its proper divisors (42996324).

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

21964572 is a wasteful number, since it uses less digits than its factorization.

21964572 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2087 (or 2082 counting only the distinct ones).

The product of its digits is 30240, while the sum is 36.

The square root of 21964572 is about 4686.6376006685. The cubic root of 21964572 is about 280.0534421801.

The spelling of 21964572 in words is "twenty-one million, nine hundred sixty-four thousand, five hundred seventy-two".