81635198371 has 4 divisors (see below), whose sum is σ = 81830032200. Its totient is φ = 81440364544.

The previous prime is 81635198369. The next prime is 81635198377. The reversal of 81635198371 is 17389153618.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81635198371 - 2¹ = 81635198369 is a prime.

It is a super-2 number, since 2×81635198371² (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 (81635198377) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 97416286 + ... + 97417123.

It is an arithmetic number, because the mean of its divisors is an integer number (20457508050).

Almost surely, 2^81635198371 is an apocalyptic number.

81635198371 is a deficient number, since it is larger than the sum of its proper divisors (194833829).

81635198371 is a wasteful number, since it uses less digits than its factorization.

81635198371 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194833828.

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

The spelling of 81635198371 in words is "eighty-one billion, six hundred thirty-five million, one hundred ninety-eight thousand, three hundred seventy-one".