81709637500 has 36 divisors (see below), whose sum is σ = 178728420024. Its totient is φ = 32683850000.

The previous prime is 81709637491. The next prime is 81709637563. The reversal of 81709637500 is 573690718.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3255886 + ... + 3280885.

It is an arithmetic number, because the mean of its divisors is an integer number (4964678334).

Almost surely, 2^81709637500 is an apocalyptic number.

It is an amenable number.

81709637500 is an abundant number, since it is smaller than the sum of its proper divisors (97018782524).

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

81709637500 is an equidigital number, since it uses as much as digits as its factorization.

81709637500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6536800 (or 6536778 counting only the distinct ones).

The product of its (nonzero) digits is 317520, while the sum is 46.

The spelling of 81709637500 in words is "eighty-one billion, seven hundred nine million, six hundred thirty-seven thousand, five hundred".