65291390640 has 360 divisors, whose sum is σ = 257712567840. Its totient is φ = 14769119232.

The previous prime is 65291390611. The next prime is 65291390641. The reversal of 65291390640 is 4609319256.

It is a tau number, because it is divible by the number of its divisors (360).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (65291390641) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 3412621 + ... + 3431699.

It is an arithmetic number, because the mean of its divisors is an integer number (715868244).

Almost surely, 2^65291390640 is an apocalyptic number.

65291390640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 65291390640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128856283920).

65291390640 is an abundant number, since it is smaller than the sum of its proper divisors (192421177200).

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

65291390640 is a wasteful number, since it uses less digits than its factorization.

65291390640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19209 (or 19193 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 45.

The spelling of 65291390640 in words is "sixty-five billion, two hundred ninety-one million, three hundred ninety thousand, six hundred forty".