81975133969 has 9 divisors (see below), whose sum is σ = 82932331377. Its totient is φ = 81028869504.

The previous prime is 81975133967. The next prime is 81975134027. The reversal of 81975133969 is 96933157918.

The square root of 81975133969 is 286313.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 1482635025 + 80492498944 = 38505^2 + 283712^2 .

It is not a de Polignac number, because 81975133969 - 2¹ = 81975133967 is a prime.

It is a super-2 number, since 2×81975133969² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81975133967) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 25480249 + ... + 25483465.

Almost surely, 2^81975133969 is an apocalyptic number.

81975133969 is a gapful number since it is divisible by the number (89) formed by its first and last digit.

81975133969 is the 286313-rd square number.

81975133969 is the 143157-th centered octagonal number.

It is an amenable number.

81975133969 is a deficient number, since it is larger than the sum of its proper divisors (957197408).

81975133969 is an frugal number, since it uses more digits than its factorization.

81975133969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6612 (or 3306 counting only the distinct ones).

The product of its digits is 11022480, while the sum is 61.

The spelling of 81975133969 in words is "eighty-one billion, nine hundred seventy-five million, one hundred thirty-three thousand, nine hundred sixty-nine".