81493120900 has 27 divisors (see below), whose sum is σ = 176846267269. Its totient is φ = 32596106480.

The previous prime is 81493120889. The next prime is 81493120903. The reversal of 81493120900 is 902139418.

The square root of 81493120900 is 285470.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 29337523524 + 52155597376 = 171282^2 + 228376^2 .

It is a super-2 number, since 2×81493120900² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81493120900.

It is not an unprimeable number, because it can be changed into a prime (81493120903) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2840427 + ... + 2868973.

Almost surely, 2^81493120900 is an apocalyptic number.

81493120900 is the 285470-th square number.

It is an amenable number.

81493120900 is an abundant number, since it is smaller than the sum of its proper divisors (95353146369).

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

81493120900 is an frugal number, since it uses more digits than its factorization.

81493120900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57108 (or 28554 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 37.

The spelling of 81493120900 in words is "eighty-one billion, four hundred ninety-three million, one hundred twenty thousand, nine hundred".