81575741520 has 1120 divisors, whose sum is σ = 368863891200. Its totient is φ = 16285556736.

The previous prime is 81575741483. The next prime is 81575741543. The reversal of 81575741520 is 2514757518.

81575741520 is a `hidden beast` number, since 8 + 1 + 57 + 5 + 74 + 1 + 520 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 223 ways as a sum of consecutive naturals, for example, 100834876 + ... + 100835684.

It is an arithmetic number, because the mean of its divisors is an integer number (329342760).

Almost surely, 2^81575741520 is an apocalyptic number.

81575741520 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 81575741520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (184431945600).

81575741520 is an abundant number, since it is smaller than the sum of its proper divisors (287288149680).

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

81575741520 is a wasteful number, since it uses less digits than its factorization.

81575741520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 879 (or 858 counting only the distinct ones).

The product of its (nonzero) digits is 392000, while the sum is 45.

The spelling of 81575741520 in words is "eighty-one billion, five hundred seventy-five million, seven hundred forty-one thousand, five hundred twenty".