81400728 has 16 divisors (see below), whose sum is σ = 203501880. Its totient is φ = 27133568.

The previous prime is 81400721. The next prime is 81400729. The reversal of 81400728 is 82700418.

It is a junction number, because it is equal to n+sod(n) for n = 81400695 and 81400704.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81400721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1695825 + ... + 1695872.

Almost surely, 2^81400728 is an apocalyptic number.

It is an amenable number.

81400728 is an abundant number, since it is smaller than the sum of its proper divisors (122101152).

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

81400728 is a wasteful number, since it uses less digits than its factorization.

81400728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3391706 (or 3391702 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 81400728 is about 9022.2351997717. The cubic root of 81400728 is about 433.3872159164.

It can be divided in two parts, 81400 and 728, that added together give a palindrome (82128).

The spelling of 81400728 in words is "eighty-one million, four hundred thousand, seven hundred twenty-eight".