21964542 has 16 divisors (see below), whose sum is σ = 45444240. Its totient is φ = 7068992.

The previous prime is 21964541. The next prime is 21964549. The reversal of 21964542 is 24546912.

It is a super-2 number, since 2×21964542² = 964882210539528, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21964541) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 62943 + ... + 63290.

It is an arithmetic number, because the mean of its divisors is an integer number (2840265).

Almost surely, 2^21964542 is an apocalyptic number.

21964542 is an abundant number, since it is smaller than the sum of its proper divisors (23479698).

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

21964542 is a wasteful number, since it uses less digits than its factorization.

21964542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126267.

The product of its digits is 17280, while the sum is 33.

The square root of 21964542 is about 4686.6344000786. The cubic root of 21964542 is about 280.0533146777.

The spelling of 21964542 in words is "twenty-one million, nine hundred sixty-four thousand, five hundred forty-two".