81280872 has 24 divisors (see below), whose sum is σ = 220135890. Its totient is φ = 27093600.

The previous prime is 81280811. The next prime is 81280891. The reversal of 81280872 is 27808218.

It can be written as a sum of positive squares in only one way, i.e., 50211396 + 31069476 = 7086^2 + 5574^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 564379 + ... + 564522.

Almost surely, 2^81280872 is an apocalyptic number.

It is an amenable number.

81280872 is an abundant number, since it is smaller than the sum of its proper divisors (138855018).

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

81280872 is a wasteful number, since it uses less digits than its factorization.

81280872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1128913 (or 1128906 counting only the distinct ones).

The product of its (nonzero) digits is 14336, while the sum is 36.

The square root of 81280872 is about 9015.5904964678. The cubic root of 81280872 is about 433.1744022034.

The spelling of 81280872 in words is "eighty-one million, two hundred eighty thousand, eight hundred seventy-two".