81635191790 has 16 divisors (see below), whose sum is σ = 147574007568. Its totient is φ = 32513929536.

The previous prime is 81635191783. The next prime is 81635191801. The reversal of 81635191790 is 9719153618.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17515952 + ... + 17520611.

It is an arithmetic number, because the mean of its divisors is an integer number (9223375473).

Almost surely, 2^81635191790 is an apocalyptic number.

81635191790 is a deficient number, since it is larger than the sum of its proper divisors (65938815778).

81635191790 is a wasteful number, since it uses less digits than its factorization.

81635191790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35036803.

The product of its (nonzero) digits is 408240, while the sum is 50.

The spelling of 81635191790 in words is "eighty-one billion, six hundred thirty-five million, one hundred ninety-one thousand, seven hundred ninety".