21029986 has 32 divisors (see below), whose sum is σ = 34925040. Its totient is φ = 9455616.

The previous prime is 21029977. The next prime is 21030001. The reversal of 21029986 is 68992012.

It can be written as a sum of positive squares in 8 ways, for example, as 20748025 + 281961 = 4555^2 + 531^2 .

It is a super-2 number, since 2×21029986² = 884520622320392, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 91720 + ... + 91948.

Almost surely, 2^21029986 is an apocalyptic number.

21029986 is a deficient number, since it is larger than the sum of its proper divisors (13895054).

21029986 is a wasteful number, since it uses less digits than its factorization.

21029986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 358.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 21029986 is about 4585.8462686837. The cubic root of 21029986 is about 276.0236712177.

The spelling of 21029986 in words is "twenty-one million, twenty-nine thousand, nine hundred eighty-six".