21189942 has 12 divisors (see below), whose sum is σ = 45911580. Its totient is φ = 7063308.

The previous prime is 21189919. The next prime is 21189943. The reversal of 21189942 is 24998112.

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

It is a junction number, because it is equal to n+sod(n) for n = 21189897 and 21189906.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21189943) 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, 588592 + ... + 588627.

It is an arithmetic number, because the mean of its divisors is an integer number (3825965).

Almost surely, 2^21189942 is an apocalyptic number.

21189942 is an abundant number, since it is smaller than the sum of its proper divisors (24721638).

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

21189942 is a wasteful number, since it uses less digits than its factorization.

21189942 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1177227 (or 1177224 counting only the distinct ones).

The product of its digits is 10368, while the sum is 36.

The square root of 21189942 is about 4603.2534147057. The cubic root of 21189942 is about 276.7217248209.

The spelling of 21189942 in words is "twenty-one million, one hundred eighty-nine thousand, nine hundred forty-two".