864521281440 has 960 divisors, whose sum is σ = 3216735244800. Its totient is φ = 218466533376.

The previous prime is 864521281373. The next prime is 864521281453. The reversal of 864521281440 is 44182125468.

864521281440 is a `hidden beast` number, since 8 + 6 + 4 + 521 + 2 + 81 + 4 + 40 = 666.

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 159 ways as a sum of consecutive naturals, for example, 3213833626 + ... + 3213833894.

It is an arithmetic number, because the mean of its divisors is an integer number (3350765880).

Almost surely, 2^864521281440 is an apocalyptic number.

864521281440 is a gapful number since it is divisible by the number (80) 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 864521281440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1608367622400).

864521281440 is an abundant number, since it is smaller than the sum of its proper divisors (2352213963360).

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

864521281440 is a wasteful number, since it uses less digits than its factorization.

864521281440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 491 (or 474 counting only the distinct ones).

The product of its (nonzero) digits is 491520, while the sum is 45.

The spelling of 864521281440 in words is "eight hundred sixty-four billion, five hundred twenty-one million, two hundred eighty-one thousand, four hundred forty".