64919931 has 4 divisors (see below), whose sum is σ = 86559912. Its totient is φ = 43279952.

The previous prime is 64919929. The next prime is 64919963. The reversal of 64919931 is 13991946.

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 64919931 - 2¹ = 64919929 is a prime.

It is a super-2 number, since 2×64919931² = 8429194882089522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (64919431) 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, 10819986 + ... + 10819991.

It is an arithmetic number, because the mean of its divisors is an integer number (21639978).

Almost surely, 2^64919931 is an apocalyptic number.

64919931 is a deficient number, since it is larger than the sum of its proper divisors (21639981).

64919931 is a wasteful number, since it uses less digits than its factorization.

64919931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21639980.

The product of its digits is 52488, while the sum is 42.

The square root of 64919931 is about 8057.2905495582. The cubic root of 64919931 is about 401.9074128993.

It can be divided in two parts, 649199 and 31, that added together give a triangular number (649230 = T₁₁₃₉).

The spelling of 64919931 in words is "sixty-four million, nine hundred nineteen thousand, nine hundred thirty-one".