64910891520 has 240 divisors, whose sum is σ = 225547954632. Its totient is φ = 17252352000.

The previous prime is 64910891489. The next prime is 64910891543. The reversal of 64910891520 is 2519801946.

64910891520 is a `hidden beast` number, since 6 + 49 + 1 + 0 + 89 + 1 + 520 = 666.

64910891520 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 19470295296 + 45440596224 = 139536^2 + 213168^2 .

It is a tau number, because it is divible by the number of its divisors (240).

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

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7207020 + ... + 7216020.

Almost surely, 2^64910891520 is an apocalyptic number.

64910891520 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 64910891520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (112773977316).

64910891520 is an abundant number, since it is smaller than the sum of its proper divisors (160637063112).

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

64910891520 is a wasteful number, since it uses less digits than its factorization.

64910891520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9343 (or 9324 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 45.

The spelling of 64910891520 in words is "sixty-four billion, nine hundred ten million, eight hundred ninety-one thousand, five hundred twenty".