172581785681 has 2 divisors, whose sum is σ = 172581785682. Its totient is φ = 172581785680.

The previous prime is 172581785659. The next prime is 172581785771. The reversal of 172581785681 is 186587185271.

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., 137718921025 + 34862864656 = 371105^2 + 186716^2 .

It is a cyclic number.

It is not a de Polignac number, because 172581785681 - 2¹⁰ = 172581784657 is a prime.

It is a super-2 number, since 2×172581785681² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 172581785681.

It is not a weakly prime, because it can be changed into another prime (172581781681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86290892840 + 86290892841.

It is an arithmetic number, because the mean of its divisors is an integer number (86290892841).

Almost surely, 2^172581785681 is an apocalyptic number.

It is an amenable number.

172581785681 is a deficient number, since it is larger than the sum of its proper divisors (1).

172581785681 is an equidigital number, since it uses as much as digits as its factorization.

172581785681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7526400, while the sum is 59.

The spelling of 172581785681 in words is "one hundred seventy-two billion, five hundred eighty-one million, seven hundred eighty-five thousand, six hundred eighty-one".