81172298653 has 2 divisors, whose sum is σ = 81172298654. Its totient is φ = 81172298652.

The previous prime is 81172298651. The next prime is 81172298729. The reversal of 81172298653 is 35689227118.

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., 61602247204 + 19570051449 = 248198^2 + 139893^2 .

It is a cyclic number.

It is not a de Polignac number, because 81172298653 - 2¹ = 81172298651 is a prime.

It is a super-2 number, since 2×81172298653² (a number of 23 digits) contains 22 as substring.

Together with 81172298651, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 81172298653.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81172298651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40586149326 + 40586149327.

It is an arithmetic number, because the mean of its divisors is an integer number (40586149327).

Almost surely, 2^81172298653 is an apocalyptic number.

It is an amenable number.

81172298653 is a deficient number, since it is larger than the sum of its proper divisors (1).

81172298653 is an equidigital number, since it uses as much as digits as its factorization.

81172298653 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1451520, while the sum is 52.

The spelling of 81172298653 in words is "eighty-one billion, one hundred seventy-two million, two hundred ninety-eight thousand, six hundred fifty-three".