81780749824 has 160 divisors (see below), whose sum is σ = 175988736000. Its totient is φ = 37878865920.

The previous prime is 81780749821. The next prime is 81780749887. The reversal of 81780749824 is 42894708718.

It is a Harshad number since it is a multiple of its sum of digits (58).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81780749821) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 58455877 + ... + 58457275.

It is an arithmetic number, because the mean of its divisors is an integer number (1099929600).

Almost surely, 2^81780749824 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 81780749824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87994368000).

81780749824 is an abundant number, since it is smaller than the sum of its proper divisors (94207986176).

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

81780749824 is a wasteful number, since it uses less digits than its factorization.

81780749824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1604 (or 1588 counting only the distinct ones).

The product of its (nonzero) digits is 7225344, while the sum is 58.

The spelling of 81780749824 in words is "eighty-one billion, seven hundred eighty million, seven hundred forty-nine thousand, eight hundred twenty-four".