81612900 has 144 divisors (see below), whose sum is σ = 265399680. Its totient is φ = 21513600.

The previous prime is 81612899. The next prime is 81612907. The reversal of 81612900 is 921618.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (81612907) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 450810 + ... + 450990.

Almost surely, 2^81612900 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 81612900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132699840).

81612900 is an abundant number, since it is smaller than the sum of its proper divisors (183786780).

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

81612900 is a wasteful number, since it uses less digits than its factorization.

81612900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 371 (or 358 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 81612900 is about 9033.9858312929. The cubic root of 81612900 is about 433.7634322732.

The spelling of 81612900 in words is "eighty-one million, six hundred twelve thousand, nine hundred".