81751781124 has 144 divisors (see below), whose sum is σ = 225809059840. Its totient is φ = 24788332800.

The previous prime is 81751781101. The next prime is 81751781191. The reversal of 81751781124 is 42118715718.

81751781124 is a `hidden beast` number, since 8 + 1 + 7 + 517 + 8 + 1 + 124 = 666.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 81751781124.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 8970282 + ... + 8979390.

Almost surely, 2^81751781124 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81751781124, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (112904529920).

81751781124 is an abundant number, since it is smaller than the sum of its proper divisors (144057278716).

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

81751781124 is a wasteful number, since it uses less digits than its factorization.

81751781124 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9410 (or 9405 counting only the distinct ones).

The product of its digits is 125440, while the sum is 45.

The spelling of 81751781124 in words is "eighty-one billion, seven hundred fifty-one million, seven hundred eighty-one thousand, one hundred twenty-four".