81198988990 has 32 divisors (see below), whose sum is σ = 171552464064. Its totient is φ = 27087229440.

The previous prime is 81198988979. The next prime is 81198988991. The reversal of 81198988990 is 9988989118.

It is a Harshad number since it is a multiple of its sum of digits (70).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81198988991) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15672891 + ... + 15678070.

It is an arithmetic number, because the mean of its divisors is an integer number (5361014502).

Almost surely, 2^81198988990 is an apocalyptic number.

81198988990 is an abundant number, since it is smaller than the sum of its proper divisors (90353475074).

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

81198988990 is a wasteful number, since it uses less digits than its factorization.

81198988990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31351012.

The product of its (nonzero) digits is 26873856, while the sum is 70.

The spelling of 81198988990 in words is "eighty-one billion, one hundred ninety-eight million, nine hundred eighty-eight thousand, nine hundred ninety".