21940989 has 8 divisors (see below), whose sum is σ = 33433920. Its totient is φ = 12537696.

The previous prime is 21940981. The next prime is 21941021. The reversal of 21940989 is 98904912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21940989 - 2³ = 21940981 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21940989.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21940981) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 522384 + ... + 522425.

It is an arithmetic number, because the mean of its divisors is an integer number (4179240).

Almost surely, 2^21940989 is an apocalyptic number.

It is an amenable number.

21940989 is a deficient number, since it is larger than the sum of its proper divisors (11492931).

21940989 is a wasteful number, since it uses less digits than its factorization.

21940989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1044819.

The product of its (nonzero) digits is 46656, while the sum is 42.

The square root of 21940989 is about 4684.1209420765. The cubic root of 21940989 is about 279.9531766942.

The spelling of 21940989 in words is "twenty-one million, nine hundred forty thousand, nine hundred eighty-nine".