21164986 has 4 divisors (see below), whose sum is σ = 31747482. Its totient is φ = 10582492.

The previous prime is 21164953. The next prime is 21164989. The reversal of 21164986 is 68946112.

It is a happy number.

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., 10725625 + 10439361 = 3275^2 + 3231^2 .

It is not an unprimeable number, because it can be changed into a prime (21164989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5291245 + ... + 5291248.

Almost surely, 2^21164986 is an apocalyptic number.

21164986 is a deficient number, since it is larger than the sum of its proper divisors (10582496).

21164986 is a wasteful number, since it uses less digits than its factorization.

21164986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10582495.

The product of its digits is 20736, while the sum is 37.

The square root of 21164986 is about 4600.5419245998. The cubic root of 21164986 is about 276.6130477856.

The spelling of 21164986 in words is "twenty-one million, one hundred sixty-four thousand, nine hundred eighty-six".