81739919232 has 256 divisors, whose sum is σ = 245401228800. Its totient is φ = 26780921856.

The previous prime is 81739919143. The next prime is 81739919243. The reversal of 81739919232 is 23291993718.

81739919232 is a `hidden beast` number, since 8 + 1 + 7 + 399 + 19 + 232 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 66834973 + ... + 66836195.

It is an arithmetic number, because the mean of its divisors is an integer number (958598550).

Almost surely, 2^81739919232 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 81739919232, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122700614400).

81739919232 is an abundant number, since it is smaller than the sum of its proper divisors (163661309568).

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

81739919232 is a wasteful number, since it uses less digits than its factorization.

81739919232 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1562 (or 1544 counting only the distinct ones).

The product of its digits is 1469664, while the sum is 54.

The spelling of 81739919232 in words is "eighty-one billion, seven hundred thirty-nine million, nine hundred nineteen thousand, two hundred thirty-two".