81015800 has 48 divisors (see below), whose sum is σ = 191940840. Its totient is φ = 31790720.

The previous prime is 81015793. The next prime is 81015817. The reversal of 81015800 is 851018.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6779 + ... + 14421.

Almost surely, 2^81015800 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81015800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (95970420).

81015800 is an abundant number, since it is smaller than the sum of its proper divisors (110925040).

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

81015800 is a wasteful number, since it uses less digits than its factorization.

81015800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7712 (or 7703 counting only the distinct ones).

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

The square root of 81015800 is about 9000.8777349767. The cubic root of 81015800 is about 432.7030020326.

Adding to 81015800 its reverse (851018), we get a palindrome (81866818).

The spelling of 81015800 in words is "eighty-one million, fifteen thousand, eight hundred".