63171991 has 4 divisors (see below), whose sum is σ = 63212584. Its totient is φ = 63131400.

The previous prime is 63171973. The next prime is 63172001. The reversal of 63171991 is 19917136.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 63171991 - 2¹³ = 63163799 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 63171991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (63171971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17865 + ... + 21106.

It is an arithmetic number, because the mean of its divisors is an integer number (15803146).

Almost surely, 2^63171991 is an apocalyptic number.

63171991 is a deficient number, since it is larger than the sum of its proper divisors (40593).

63171991 is a wasteful number, since it uses less digits than its factorization.

63171991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40592.

The product of its digits is 10206, while the sum is 37.

The square root of 63171991 is about 7948.0809633521. The cubic root of 63171991 is about 398.2674880902.

The spelling of 63171991 in words is "sixty-three million, one hundred seventy-one thousand, nine hundred ninety-one".