661512843269 has 2 divisors, whose sum is σ = 661512843270. Its totient is φ = 661512843268.

The previous prime is 661512843259. The next prime is 661512843311. The reversal of 661512843269 is 962348215166.

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., 395552944900 + 265959898369 = 628930^2 + 515713^2 .

It is a cyclic number.

It is not a de Polignac number, because 661512843269 - 2¹⁶ = 661512777733 is a prime.

It is a super-2 number, since 2×661512843269² (a number of 24 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 661512843269.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661512843259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330756421634 + 330756421635.

It is an arithmetic number, because the mean of its divisors is an integer number (330756421635).

Almost surely, 2^661512843269 is an apocalyptic number.

It is an amenable number.

661512843269 is a deficient number, since it is larger than the sum of its proper divisors (1).

661512843269 is an equidigital number, since it uses as much as digits as its factorization.

661512843269 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3732480, while the sum is 53.

The spelling of 661512843269 in words is "six hundred sixty-one billion, five hundred twelve million, eight hundred forty-three thousand, two hundred sixty-nine".