21739986 has 24 divisors (see below), whose sum is σ = 47234460. Its totient is φ = 7226496.

The previous prime is 21739981. The next prime is 21739999. The reversal of 21739986 is 68993712.

It can be written as a sum of positive squares in 2 ways, for example, as 18224361 + 3515625 = 4269^2 + 1875^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21739981) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5886 + ... + 8838.

Almost surely, 2^21739986 is an apocalyptic number.

21739986 is an abundant number, since it is smaller than the sum of its proper divisors (25494474).

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

21739986 is a wasteful number, since it uses less digits than its factorization.

21739986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3370 (or 3367 counting only the distinct ones).

The product of its digits is 163296, while the sum is 45.

The square root of 21739986 is about 4662.6157894469. The cubic root of 21739986 is about 279.0956622667.

The spelling of 21739986 in words is "twenty-one million, seven hundred thirty-nine thousand, nine hundred eighty-six".