81815000 has 40 divisors (see below), whose sum is σ = 191704260. Its totient is φ = 32724000.

The previous prime is 81814981. The next prime is 81815011. The reversal of 81815000 is 51818.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 3182 + ... + 13181.

Almost surely, 2^81815000 is an apocalyptic number.

It is an amenable number.

81815000 is an abundant number, since it is smaller than the sum of its proper divisors (109889260).

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

81815000 is a wasteful number, since it uses less digits than its factorization.

81815000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16389 (or 16370 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 23.

The square root of 81815000 is about 9045.1644540052. The cubic root of 81815000 is about 434.1211834289.

Adding to 81815000 its reverse (51818), we get a palindrome (81866818).

The spelling of 81815000 in words is "eighty-one million, eight hundred fifteen thousand".