21967866 has 12 divisors (see below), whose sum is σ = 47597082. Its totient is φ = 7322616.

The previous prime is 21967853. The next prime is 21967867. The reversal of 21967866 is 66876912.

It can be written as a sum of positive squares in only one way, i.e., 21427641 + 540225 = 4629^2 + 735^2 .

It is not an unprimeable number, because it can be changed into a prime (21967867) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 610201 + ... + 610236.

Almost surely, 2^21967866 is an apocalyptic number.

21967866 is an abundant number, since it is smaller than the sum of its proper divisors (25629216).

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

21967866 is a wasteful number, since it uses less digits than its factorization.

21967866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1220445 (or 1220442 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 21967866 is about 4686.9890121484. The cubic root of 21967866 is about 280.0674412377.

The spelling of 21967866 in words is "twenty-one million, nine hundred sixty-seven thousand, eight hundred sixty-six".