81317461 has 2 divisors, whose sum is σ = 81317462. Its totient is φ = 81317460.

The previous prime is 81317441. The next prime is 81317491. The reversal of 81317461 is 16471318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 79548561 + 1768900 = 8919^2 + 1330^2 .

It is a cyclic number.

It is not a de Polignac number, because 81317461 - 2¹¹ = 81315413 is a prime.

It is a super-2 number, since 2×81317461² = 13225058926973042, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81317441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40658730 + 40658731.

It is an arithmetic number, because the mean of its divisors is an integer number (40658731).

Almost surely, 2^81317461 is an apocalyptic number.

It is an amenable number.

81317461 is a deficient number, since it is larger than the sum of its proper divisors (1).

81317461 is an equidigital number, since it uses as much as digits as its factorization.

81317461 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 31.

The square root of 81317461 is about 9017.6194752274. The cubic root of 81317461 is about 433.2393910098.

Adding to 81317461 its reverse (16471318), we get a palindrome (97788779).

The spelling of 81317461 in words is "eighty-one million, three hundred seventeen thousand, four hundred sixty-one".