81313117 has 2 divisors, whose sum is σ = 81313118. Its totient is φ = 81313116.

The previous prime is 81313109. The next prime is 81313139. The reversal of 81313117 is 71131318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77545636 + 3767481 = 8806^2 + 1941^2 .

It is a cyclic number.

It is not a de Polignac number, because 81313117 - 2³ = 81313109 is a prime.

It is a super-2 number, since 2×81313117² = 13223645992511378, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81313091 and 81313100.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81313157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40656558 + 40656559.

It is an arithmetic number, because the mean of its divisors is an integer number (40656559).

Almost surely, 2^81313117 is an apocalyptic number.

It is an amenable number.

81313117 is a deficient number, since it is larger than the sum of its proper divisors (1).

81313117 is an equidigital number, since it uses as much as digits as its factorization.

81313117 is an evil number, because the sum of its binary digits is even.

The product of its digits is 504, while the sum is 25.

The square root of 81313117 is about 9017.3786102171. The cubic root of 81313117 is about 433.2316762853.

It can be divided in two parts, 8131311 and 7, that added together give a palindrome (8131318).

The spelling of 81313117 in words is "eighty-one million, three hundred thirteen thousand, one hundred seventeen".