64309991 has 2 divisors, whose sum is σ = 64309992. Its totient is φ = 64309990.

The previous prime is 64309981. The next prime is 64310009. The reversal of 64309991 is 19990346.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-64309991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64309901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32154995 + 32154996.

It is an arithmetic number, because the mean of its divisors is an integer number (32154996).

Almost surely, 2^64309991 is an apocalyptic number.

64309991 is a deficient number, since it is larger than the sum of its proper divisors (1).

64309991 is an equidigital number, since it uses as much as digits as its factorization.

64309991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 52488, while the sum is 41.

The square root of 64309991 is about 8019.3510335937. The cubic root of 64309991 is about 400.6447746889.

The spelling of 64309991 in words is "sixty-four million, three hundred nine thousand, nine hundred ninety-one".