81997110722 has 6 divisors (see below), whose sum is σ = 122996273529. Its totient is φ = 40998352880.

The previous prime is 81997110703. The next prime is 81997110731. The reversal of 81997110722 is 22701179918.

It can be written as a sum of positive squares in 2 ways, for example, as 72618931441 + 9378179281 = 269479^2 + 96841^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=202481.

It is a super-2 number, since 2×81997110722² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 303722 + ... + 506202.

Almost surely, 2^81997110722 is an apocalyptic number.

81997110722 is a deficient number, since it is larger than the sum of its proper divisors (40999162807).

81997110722 is an frugal number, since it uses more digits than its factorization.

81997110722 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 404964 (or 202483 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 47.

The spelling of 81997110722 in words is "eighty-one billion, nine hundred ninety-seven million, one hundred ten thousand, seven hundred twenty-two".