81819090864 has 120 divisors (see below), whose sum is σ = 261756198912. Its totient is φ = 23371079040.

The previous prime is 81819090719. The next prime is 81819090923. The reversal of 81819090864 is 46809091818.

It is a super-2 number, since 2×81819090864² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81819090864.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5600209 + ... + 5614799.

Almost surely, 2^81819090864 is an apocalyptic number.

81819090864 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

81819090864 is an abundant number, since it is smaller than the sum of its proper divisors (179937108048).

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

81819090864 is a wasteful number, since it uses less digits than its factorization.

81819090864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20175 (or 20166 counting only the distinct ones).

The product of its (nonzero) digits is 995328, while the sum is 54.

The spelling of 81819090864 in words is "eighty-one billion, eight hundred nineteen million, ninety thousand, eight hundred sixty-four".