661252881672769 has 2 divisors, whose sum is σ = 661252881672770. Its totient is φ = 661252881672768.

The previous prime is 661252881672767. The next prime is 661252881672793. The reversal of 661252881672769 is 967276188252166.

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., 660051271080369 + 1201610592400 = 25691463^2 + 1096180^2 .

It is a cyclic number.

It is not a de Polignac number, because 661252881672769 - 2¹ = 661252881672767 is a prime.

It is a super-2 number, since 2×661252881672769² (a number of 30 digits) contains 22 as substring.

Together with 661252881672767, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 661252881672695 and 661252881672704.

It is not a weakly prime, because it can be changed into another prime (661252881672767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330626440836384 + 330626440836385.

It is an arithmetic number, because the mean of its divisors is an integer number (330626440836385).

Almost surely, 2^{661252881672769} is an apocalyptic number.

It is an amenable number.

661252881672769 is a deficient number, since it is larger than the sum of its proper divisors (1).

661252881672769 is an equidigital number, since it uses as much as digits as its factorization.

661252881672769 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1463132160, while the sum is 76.

The spelling of 661252881672769 in words is "six hundred sixty-one trillion, two hundred fifty-two billion, eight hundred eighty-one million, six hundred seventy-two thousand, seven hundred sixty-nine".