21866994 has 24 divisors (see below), whose sum is σ = 47473452. Its totient is φ = 7274400.

The previous prime is 21866989. The next prime is 21867019. The reversal of 21866994 is 49966812.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21206025 + 660969 = 4605^2 + 813^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11752 + ... + 13484.

Almost surely, 2^21866994 is an apocalyptic number.

21866994 is an abundant number, since it is smaller than the sum of its proper divisors (25606458).

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

21866994 is a wasteful number, since it uses less digits than its factorization.

21866994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2442 (or 2439 counting only the distinct ones).

The product of its digits is 186624, while the sum is 45.

The square root of 21866994 is about 4676.2157777417. The cubic root of 21866994 is about 279.6381124098.

It can be divided in two parts, 2186 and 6994, that added together give a triangular number (9180 = T₁₃₅).

The spelling of 21866994 in words is "twenty-one million, eight hundred sixty-six thousand, nine hundred ninety-four".