63920991 has 4 divisors (see below), whose sum is σ = 85227992. Its totient is φ = 42613992.

The previous prime is 63920951. The next prime is 63921001. The reversal of 63920991 is 19902936.

It is a happy number.

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

It is not a de Polignac number, because 63920991 - 2¹³ = 63912799 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (63920911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10653496 + ... + 10653501.

It is an arithmetic number, because the mean of its divisors is an integer number (21306998).

Almost surely, 2^63920991 is an apocalyptic number.

63920991 is a deficient number, since it is larger than the sum of its proper divisors (21307001).

63920991 is a wasteful number, since it uses less digits than its factorization.

63920991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21307000.

The product of its (nonzero) digits is 26244, while the sum is 39.

The square root of 63920991 is about 7995.0604125297. The cubic root of 63920991 is about 399.8353301356.

It can be divided in two parts, 6392099 and 1, that added together give a triangular number (6392100 = T₃₅₇₅).

The spelling of 63920991 in words is "sixty-three million, nine hundred twenty thousand, nine hundred ninety-one".