81428180 has 24 divisors (see below), whose sum is σ = 171619560. Its totient is φ = 32453120.

The previous prime is 81428101. The next prime is 81428189. The reversal of 81428180 is 8182418.

It can be written as a sum of positive squares in 4 ways, for example, as 3671056 + 77757124 = 1916^2 + 8818^2 .

It is a super-2 number, since 2×81428180² = 13261096996224800, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81428189) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1625 + ... + 12864.

It is an arithmetic number, because the mean of its divisors is an integer number (7150815).

Almost surely, 2^81428180 is an apocalyptic number.

It is an amenable number.

81428180 is an abundant number, since it is smaller than the sum of its proper divisors (90191380).

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

81428180 is a wasteful number, since it uses less digits than its factorization.

81428180 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14779 (or 14777 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 32.

The square root of 81428180 is about 9023.7564240177. The cubic root of 81428180 is about 433.4359296849.

The spelling of 81428180 in words is "eighty-one million, four hundred twenty-eight thousand, one hundred eighty".