81355800 has 48 divisors (see below), whose sum is σ = 252204840. Its totient is φ = 21694720.

The previous prime is 81355787. The next prime is 81355801. The reversal of 81355800 is 855318.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81355801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 67197 + ... + 68396.

Almost surely, 2^81355800 is an apocalyptic number.

It is an amenable number.

81355800 is an abundant number, since it is smaller than the sum of its proper divisors (170849040).

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

81355800 is a wasteful number, since it uses less digits than its factorization.

81355800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135612 (or 135603 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 30.

The square root of 81355800 is about 9019.7450074822. The cubic root of 81355800 is about 433.3074672266.

The spelling of 81355800 in words is "eighty-one million, three hundred fifty-five thousand, eight hundred".