81815340 has 48 divisors (see below), whose sum is σ = 230130432. Its totient is φ = 21717696.

The previous prime is 81815309. The next prime is 81815381. The reversal of 81815340 is 4351818.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 81815298 and 81815307.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10617 + ... + 16623.

It is an arithmetic number, because the mean of its divisors is an integer number (4794384).

Almost surely, 2^81815340 is an apocalyptic number.

It is an amenable number.

81815340 is an abundant number, since it is smaller than the sum of its proper divisors (148315092).

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

81815340 is a wasteful number, since it uses less digits than its factorization.

81815340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6246 (or 6244 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 30.

The square root of 81815340 is about 9045.1832485583. The cubic root of 81815340 is about 434.1217847897.

The spelling of 81815340 in words is "eighty-one million, eight hundred fifteen thousand, three hundred forty".