81500550 has 96 divisors (see below), whose sum is σ = 221128704. Its totient is φ = 19776000.

The previous prime is 81500521. The next prime is 81500561. The reversal of 81500550 is 5500518.

It is a self number, because there is not a number n which added to its sum of digits gives 81500550.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 78535 + ... + 79565.

It is an arithmetic number, because the mean of its divisors is an integer number (2303424).

Almost surely, 2^81500550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81500550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (110564352).

81500550 is an abundant number, since it is smaller than the sum of its proper divisors (139628154).

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

81500550 is a wasteful number, since it uses less digits than its factorization.

81500550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1094 (or 1089 counting only the distinct ones).

The product of its (nonzero) digits is 1000, while the sum is 24.

The square root of 81500550 is about 9027.7655042652. The cubic root of 81500550 is about 433.5642983080.

The spelling of 81500550 in words is "eighty-one million, five hundred thousand, five hundred fifty".