81670031 has 2 divisors, whose sum is σ = 81670032. Its totient is φ = 81670030.

The previous prime is 81670019. The next prime is 81670051. The reversal of 81670031 is 13007618.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81670031 is a prime.

It is a super-2 number, since 2×81670031² = 13339987927081922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81670051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40835015 + 40835016.

It is an arithmetic number, because the mean of its divisors is an integer number (40835016).

Almost surely, 2^81670031 is an apocalyptic number.

81670031 is a deficient number, since it is larger than the sum of its proper divisors (1).

81670031 is an equidigital number, since it uses as much as digits as its factorization.

81670031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 81670031 is about 9037.1472821903. The cubic root of 81670031 is about 433.8646236224.

Adding to 81670031 its reverse (13007618), we get a palindrome (94677649).

The spelling of 81670031 in words is "eighty-one million, six hundred seventy thousand, thirty-one".