63991971 has 8 divisors (see below), whose sum is σ = 94802960. Its totient is φ = 42661296.

The previous prime is 63991969. The next prime is 63991973. The reversal of 63991971 is 17919936.

63991971 is a `hidden beast` number, since 639 + 9 + 1 + 9 + 7 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (63991969) and next prime (63991973).

It is not a de Polignac number, because 63991971 - 2¹ = 63991969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (63991973) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1185010 + ... + 1185063.

It is an arithmetic number, because the mean of its divisors is an integer number (11850370).

Almost surely, 2^63991971 is an apocalyptic number.

63991971 is a deficient number, since it is larger than the sum of its proper divisors (30810989).

63991971 is a wasteful number, since it uses less digits than its factorization.

63991971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2370082 (or 2370076 counting only the distinct ones).

The product of its digits is 91854, while the sum is 45.

The square root of 63991971 is about 7999.4981717605. The cubic root of 63991971 is about 399.9832722171.

The spelling of 63991971 in words is "sixty-three million, nine hundred ninety-one thousand, nine hundred seventy-one".