21489966 has 12 divisors (see below), whose sum is σ = 46561632. Its totient is φ = 7163316.

The previous prime is 21489953. The next prime is 21489973. The reversal of 21489966 is 66998412.

It is a happy number.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 596926 + ... + 596961.

It is an arithmetic number, because the mean of its divisors is an integer number (3880136).

Almost surely, 2^21489966 is an apocalyptic number.

21489966 is an abundant number, since it is smaller than the sum of its proper divisors (25071666).

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

21489966 is a wasteful number, since it uses less digits than its factorization.

21489966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1193895 (or 1193892 counting only the distinct ones).

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

The square root of 21489966 is about 4635.7271274310. The cubic root of 21489966 is about 278.0216241827.

The spelling of 21489966 in words is "twenty-one million, four hundred eighty-nine thousand, nine hundred sixty-six".