81560657 has 2 divisors, whose sum is σ = 81560658. Its totient is φ = 81560656.

The previous prime is 81560639. The next prime is 81560669. The reversal of 81560657 is 75606518.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58125376 + 23435281 = 7624^2 + 4841^2 .

It is a cyclic number.

It is not a de Polignac number, because 81560657 - 2¹⁶ = 81495121 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81560657.

It is not a weakly prime, because it can be changed into another prime (81560257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40780328 + 40780329.

It is an arithmetic number, because the mean of its divisors is an integer number (40780329).

Almost surely, 2^81560657 is an apocalyptic number.

It is an amenable number.

81560657 is a deficient number, since it is larger than the sum of its proper divisors (1).

81560657 is an equidigital number, since it uses as much as digits as its factorization.

81560657 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 50400, while the sum is 38.

The square root of 81560657 is about 9031.0938983049. The cubic root of 81560657 is about 433.6708572837.

The spelling of 81560657 in words is "eighty-one million, five hundred sixty thousand, six hundred fifty-seven".