81144980 has 72 divisors (see below), whose sum is σ = 204696576. Its totient is φ = 26913600.

The previous prime is 81144971. The next prime is 81144997. The reversal of 81144980 is 8944118.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 81144980.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 29045 + ... + 31715.

It is an arithmetic number, because the mean of its divisors is an integer number (2843008).

Almost surely, 2^81144980 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 81144980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (102348288).

81144980 is an abundant number, since it is smaller than the sum of its proper divisors (123551596).

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

81144980 is a wasteful number, since it uses less digits than its factorization.

81144980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2725 (or 2716 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 35.

The square root of 81144980 is about 9008.0508435510. The cubic root of 81144980 is about 432.9328620969.

The spelling of 81144980 in words is "eighty-one million, one hundred forty-four thousand, nine hundred eighty".