64809931 has 4 divisors (see below), whose sum is σ = 68221000. Its totient is φ = 61398864.

The previous prime is 64809923. The next prime is 64809947. The reversal of 64809931 is 13990846.

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 64809931 - 2³ = 64809923 is a prime.

It is a super-2 number, since 2×64809931² = 8400654312449522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64809991) 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, 1705506 + ... + 1705543.

It is an arithmetic number, because the mean of its divisors is an integer number (17055250).

Almost surely, 2^64809931 is an apocalyptic number.

64809931 is a deficient number, since it is larger than the sum of its proper divisors (3411069).

64809931 is a wasteful number, since it uses less digits than its factorization.

64809931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3411068.

The product of its (nonzero) digits is 46656, while the sum is 40.

The square root of 64809931 is about 8050.4615395641. The cubic root of 64809931 is about 401.6802879476.

The spelling of 64809931 in words is "sixty-four million, eight hundred nine thousand, nine hundred thirty-one".