81532791261601 has 3 divisors (see below), whose sum is σ = 81532800291153. Its totient is φ = 81532782232050.

The previous prime is 81532791261521. The next prime is 81532791261611. The reversal of 81532791261601 is 10616219723518.

The square root of 81532791261601 is 9029551.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 81532791261601 - 2¹⁷ = 81532791130529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81532791261611) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4514776 + ... + 13544326.

It is an arithmetic number, because the mean of its divisors is an integer number (27177600097051).

Almost surely, 2^{81532791261601} is an apocalyptic number.

81532791261601 is the 9029551-st square number.

81532791261601 is the 4514776-th centered octagonal number.

It is an amenable number.

81532791261601 is a deficient number, since it is larger than the sum of its proper divisors (9029552).

81532791261601 is an frugal number, since it uses more digits than its factorization.

81532791261601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18059102 (or 9029551 counting only the distinct ones).

The product of its (nonzero) digits is 1088640, while the sum is 52.

The spelling of 81532791261601 in words is "eighty-one trillion, five hundred thirty-two billion, seven hundred ninety-one million, two hundred sixty-one thousand, six hundred one".