81679900 has 72 divisors (see below), whose sum is σ = 195924960. Its totient is φ = 29399040.

The previous prime is 81679889. The next prime is 81679907. The reversal of 81679900 is 997618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81679907) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 38056 + ... + 40144.

It is an arithmetic number, because the mean of its divisors is an integer number (2721180).

Almost surely, 2^81679900 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 81679900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (97962480).

81679900 is an abundant number, since it is smaller than the sum of its proper divisors (114245060).

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

81679900 is a wasteful number, since it uses less digits than its factorization.

81679900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2143 (or 2136 counting only the distinct ones).

The product of its (nonzero) digits is 27216, while the sum is 40.

The square root of 81679900 is about 9037.6932897726. The cubic root of 81679900 is about 433.8820989739.

The spelling of 81679900 in words is "eighty-one million, six hundred seventy-nine thousand, nine hundred".