21965418 has 20 divisors (see below), whose sum is σ = 49219170. Its totient is φ = 7321752.

The previous prime is 21965417. The next prime is 21965423. The reversal of 21965418 is 81456912.

21965418 is a `hidden beast` number, since 21 + 96 + 541 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 12766329 + 9199089 = 3573^2 + 3033^2 .

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21965413) 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 9 ways as a sum of consecutive naturals, for example, 67633 + ... + 67956.

Almost surely, 2^21965418 is an apocalyptic number.

21965418 is an abundant number, since it is smaller than the sum of its proper divisors (27253752).

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

21965418 is a wasteful number, since it uses less digits than its factorization.

21965418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135603 (or 135594 counting only the distinct ones).

The product of its digits is 17280, while the sum is 36.

The square root of 21965418 is about 4686.7278564047. The cubic root of 21965418 is about 280.0570377000.

The spelling of 21965418 in words is "twenty-one million, nine hundred sixty-five thousand, four hundred eighteen".