63991986 has 24 divisors (see below), whose sum is σ = 129371760. Its totient is φ = 21100752.

The previous prime is 63991973. The next prime is 63991997. The reversal of 63991986 is 68919936.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 230880 + ... + 231156.

It is an arithmetic number, because the mean of its divisors is an integer number (5390490).

Almost surely, 2^63991986 is an apocalyptic number.

63991986 is an abundant number, since it is smaller than the sum of its proper divisors (65379774).

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

63991986 is a wasteful number, since it uses less digits than its factorization.

63991986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 698 (or 421 counting only the distinct ones).

The product of its digits is 629856, while the sum is 51.

The square root of 63991986 is about 7999.4991093193. The cubic root of 63991986 is about 399.9833034697.

It can be divided in two parts, 6399 and 1986, that added together give a triangular number (8385 = T₁₂₉).

The spelling of 63991986 in words is "sixty-three million, nine hundred ninety-one thousand, nine hundred eighty-six".