65918640 has 40 divisors (see below), whose sum is σ = 204348528. Its totient is φ = 17578240.

The previous prime is 65918609. The next prime is 65918647. The reversal of 65918640 is 4681956.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (65918647) 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, 137091 + ... + 137570.

Almost surely, 2^65918640 is an apocalyptic number.

65918640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

65918640 is an abundant number, since it is smaller than the sum of its proper divisors (138429888).

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

65918640 is a wasteful number, since it uses less digits than its factorization.

65918640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274677 (or 274671 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 39.

The square root of 65918640 is about 8119.0294986531. The cubic root of 65918640 is about 403.9578755543.

The spelling of 65918640 in words is "sixty-five million, nine hundred eighteen thousand, six hundred forty".