64689640 has 32 divisors (see below), whose sum is σ = 145790280. Its totient is φ = 25833472.

The previous prime is 64689637. The next prime is 64689643. The reversal of 64689640 is 4698646.

It is an interprime number because it is at equal distance from previous prime (64689637) and next prime (64689643).

It can be written as a sum of positive squares in 4 ways, for example, as 61873956 + 2815684 = 7866^2 + 1678^2 .

It is not an unprimeable number, because it can be changed into a prime (64689643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37272 + ... + 38968.

Almost surely, 2^64689640 is an apocalyptic number.

It is an amenable number.

64689640 is an abundant number, since it is smaller than the sum of its proper divisors (81100640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

64689640 is a wasteful number, since it uses less digits than its factorization.

64689640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2661 (or 2657 counting only the distinct ones).

The product of its (nonzero) digits is 248832, while the sum is 43.

The square root of 64689640 is about 8042.9870073251. The cubic root of 64689640 is about 401.4316200473.

The spelling of 64689640 in words is "sixty-four million, six hundred eighty-nine thousand, six hundred forty".