63747991 has 4 divisors (see below), whose sum is σ = 63931000. Its totient is φ = 63564984.

The previous prime is 63747979. The next prime is 63748001. The reversal of 63747991 is 19974736.

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 63747991 - 2⁷ = 63747863 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 (63747911) 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, 90981 + ... + 91678.

It is an arithmetic number, because the mean of its divisors is an integer number (15982750).

Almost surely, 2^63747991 is an apocalyptic number.

63747991 is a deficient number, since it is larger than the sum of its proper divisors (183009).

63747991 is a wasteful number, since it uses less digits than its factorization.

63747991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183008.

The product of its digits is 285768, while the sum is 46.

The square root of 63747991 is about 7984.2339018844. The cubic root of 63747991 is about 399.4742906268.

It can be divided in two parts, 6374 and 7991, that added together give a triangular number (14365 = T₁₆₉).

The spelling of 63747991 in words is "sixty-three million, seven hundred forty-seven thousand, nine hundred ninety-one".