81685289590 has 16 divisors (see below), whose sum is σ = 153426283488. Its totient is φ = 31253502016.

The previous prime is 81685289563. The next prime is 81685289591. The reversal of 81685289590 is 9598258618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81685289591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 177576487 + ... + 177576946.

It is an arithmetic number, because the mean of its divisors is an integer number (9589142718).

Almost surely, 2^81685289590 is an apocalyptic number.

81685289590 is a deficient number, since it is larger than the sum of its proper divisors (71740993898).

81685289590 is a wasteful number, since it uses less digits than its factorization.

81685289590 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355153463.

The product of its (nonzero) digits is 12441600, while the sum is 61.

The spelling of 81685289590 in words is "eighty-one billion, six hundred eighty-five million, two hundred eighty-nine thousand, five hundred ninety".