81180613 has 2 divisors, whose sum is σ = 81180614. Its totient is φ = 81180612.

The previous prime is 81180611. The next prime is 81180623. The reversal of 81180613 is 31608118.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 79887844 + 1292769 = 8938^2 + 1137^2 .

It is a cyclic number.

It is not a de Polignac number, because 81180613 - 2¹ = 81180611 is a prime.

Together with 81180611, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81180611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40590306 + 40590307.

It is an arithmetic number, because the mean of its divisors is an integer number (40590307).

Almost surely, 2^81180613 is an apocalyptic number.

It is an amenable number.

81180613 is a deficient number, since it is larger than the sum of its proper divisors (1).

81180613 is an equidigital number, since it uses as much as digits as its factorization.

81180613 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 81180613 is about 9010.0284683235. The cubic root of 81180613 is about 432.9962237455.

The spelling of 81180613 in words is "eighty-one million, one hundred eighty thousand, six hundred thirteen".