64078991 has 4 divisors (see below), whose sum is σ = 64981584. Its totient is φ = 63176400.

The previous prime is 64078979. The next prime is 64078997. The reversal of 64078991 is 19987046.

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 64078991 - 2²² = 59884687 is a prime.

It is a super-2 number, since 2×64078991² = 8212234175156162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64078997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 451190 + ... + 451331.

It is an arithmetic number, because the mean of its divisors is an integer number (16245396).

Almost surely, 2^64078991 is an apocalyptic number.

64078991 is a deficient number, since it is larger than the sum of its proper divisors (902593).

64078991 is an equidigital number, since it uses as much as digits as its factorization.

64078991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 902592.

The product of its (nonzero) digits is 108864, while the sum is 44.

The square root of 64078991 is about 8004.9354151049. The cubic root of 64078991 is about 400.1644969260.

The spelling of 64078991 in words is "sixty-four million, seventy-eight thousand, nine hundred ninety-one".