81959023890 has 48 divisors (see below), whose sum is σ = 213704127000. Its totient is φ = 21793107456.

The previous prime is 81959023889. The next prime is 81959023891. The reversal of 81959023890 is 9832095918.

81959023890 is a `hidden beast` number, since 8 + 19 + 590 + 2 + 38 + 9 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (81959023889) and next prime (81959023891).

It can be written as a sum of positive squares in 4 ways, for example, as 57385639809 + 24573384081 = 239553^2 + 156759^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81959023891) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1273255 + ... + 1336074.

Almost surely, 2^81959023890 is an apocalyptic number.

81959023890 is an abundant number, since it is smaller than the sum of its proper divisors (131745103110).

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

81959023890 is a wasteful number, since it uses less digits than its factorization.

81959023890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2609691 (or 2609688 counting only the distinct ones).

The product of its (nonzero) digits is 1399680, while the sum is 54.

The spelling of 81959023890 in words is "eighty-one billion, nine hundred fifty-nine million, twenty-three thousand, eight hundred ninety".