81850580 has 90 divisors (see below), whose sum is σ = 212445954. Its totient is φ = 26412288.

The previous prime is 81850579. The next prime is 81850591. The reversal of 81850580 is 8505818.

It can be written as a sum of positive squares in 5 ways, for example, as 1317904 + 80532676 = 1148^2 + 8974^2 .

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 81850580.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 4814732 + ... + 4814748.

Almost surely, 2^81850580 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 81850580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (106222977).

81850580 is an abundant number, since it is smaller than the sum of its proper divisors (130595374).

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

81850580 is an equidigital number, since it uses as much as digits as its factorization.

81850580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91 (or 31 counting only the distinct ones).

The product of its (nonzero) digits is 12800, while the sum is 35.

The square root of 81850580 is about 9047.1310369641. The cubic root of 81850580 is about 434.1841050332.

The spelling of 81850580 in words is "eighty-one million, eight hundred fifty thousand, five hundred eighty".