81163431 has 16 divisors (see below), whose sum is σ = 124389600. Its totient is φ = 52242624.

The previous prime is 81163399. The next prime is 81163447. The reversal of 81163431 is 13436118.

It is not a de Polignac number, because 81163431 - 2⁵ = 81163399 is a prime.

It is a super-2 number, since 2×81163431² = 13175005063383522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 81163395 and 81163404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81163451) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51046 + ... + 52611.

It is an arithmetic number, because the mean of its divisors is an integer number (7774350).

Almost surely, 2^81163431 is an apocalyptic number.

81163431 is a deficient number, since it is larger than the sum of its proper divisors (43226169).

81163431 is a wasteful number, since it uses less digits than its factorization.

81163431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103695 (or 103689 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 81163431 is about 9009.0749247634. The cubic root of 81163431 is about 432.9656734874.

Adding to 81163431 its reverse (13436118), we get a palindrome (94599549).

The spelling of 81163431 in words is "eighty-one million, one hundred sixty-three thousand, four hundred thirty-one".