64640640136 has 16 divisors (see below), whose sum is σ = 124476908940. Its totient is φ = 31446797760.

The previous prime is 64640640101. The next prime is 64640640137. The reversal of 64640640136 is 63104604646.

It can be written as a sum of positive squares in 2 ways, for example, as 62705168100 + 1935472036 = 250410^2 + 43994^2 .

It is not an unprimeable number, because it can be changed into a prime (64640640137) 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, 109189975 + ... + 109190566.

Almost surely, 2^64640640136 is an apocalyptic number.

It is an amenable number.

64640640136 is a deficient number, since it is larger than the sum of its proper divisors (59836268804).

64640640136 is a wasteful number, since it uses less digits than its factorization.

64640640136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218380584 (or 218380580 counting only the distinct ones).

The product of its (nonzero) digits is 248832, while the sum is 40.

The spelling of 64640640136 in words is "sixty-four billion, six hundred forty million, six hundred forty thousand, one hundred thirty-six".