21872986 has 4 divisors (see below), whose sum is σ = 32809482. Its totient is φ = 10936492.

The previous prime is 21872959. The next prime is 21872987. The reversal of 21872986 is 68927812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 13549761 + 8323225 = 3681^2 + 2885^2 .

It is not an unprimeable number, because it can be changed into a prime (21872987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5468245 + ... + 5468248.

Almost surely, 2^21872986 is an apocalyptic number.

21872986 is a deficient number, since it is larger than the sum of its proper divisors (10936496).

21872986 is a wasteful number, since it uses less digits than its factorization.

21872986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10936495.

The product of its digits is 96768, while the sum is 43.

The square root of 21872986 is about 4676.8564228550. The cubic root of 21872986 is about 279.6636522492.

The spelling of 21872986 in words is "twenty-one million, eight hundred seventy-two thousand, nine hundred eighty-six".