21918942 has 12 divisors (see below), whose sum is σ = 47491080. Its totient is φ = 7306308.

The previous prime is 21918881. The next prime is 21919003. The reversal of 21918942 is 24981912.

It is an interprime number because it is at equal distance from previous prime (21918881) and next prime (21919003).

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 = 21918897 and 21918906.

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, 608842 + ... + 608877.

It is an arithmetic number, because the mean of its divisors is an integer number (3957590).

Almost surely, 2^21918942 is an apocalyptic number.

21918942 is an abundant number, since it is smaller than the sum of its proper divisors (25572138).

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

21918942 is a wasteful number, since it uses less digits than its factorization.

21918942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1217727 (or 1217724 counting only the distinct ones).

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

The square root of 21918942 is about 4681.7669741242. The cubic root of 21918942 is about 279.8593766660.

The spelling of 21918942 in words is "twenty-one million, nine hundred eighteen thousand, nine hundred forty-two".