21646331986 has 4 divisors (see below), whose sum is σ = 32469497982. Its totient is φ = 10823165992.

The previous prime is 21646331929. The next prime is 21646332017. The reversal of 21646331986 is 68913364612.

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., 14045805225 + 7600526761 = 118515^2 + 87181^2 .

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5411582995 + ... + 5411582998.

Almost surely, 2^21646331986 is an apocalyptic number.

21646331986 is a deficient number, since it is larger than the sum of its proper divisors (10823165996).

21646331986 is a wasteful number, since it uses less digits than its factorization.

21646331986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10823165995.

The product of its digits is 1119744, while the sum is 49.

The spelling of 21646331986 in words is "twenty-one billion, six hundred forty-six million, three hundred thirty-one thousand, nine hundred eighty-six".