661969893617 has 2 divisors, whose sum is σ = 661969893618. Its totient is φ = 661969893616.

The previous prime is 661969893457. The next prime is 661969893643. The reversal of 661969893617 is 716398969166.

661969893617 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 495441423376 + 166528470241 = 703876^2 + 408079^2 .

It is a cyclic number.

It is not a de Polignac number, because 661969893617 - 2¹⁶ = 661969828081 is a prime.

It is not a weakly prime, because it can be changed into another prime (661969893317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330984946808 + 330984946809.

It is an arithmetic number, because the mean of its divisors is an integer number (330984946809).

Almost surely, 2^661969893617 is an apocalyptic number.

It is an amenable number.

661969893617 is a deficient number, since it is larger than the sum of its proper divisors (1).

661969893617 is an equidigital number, since it uses as much as digits as its factorization.

661969893617 is an evil number, because the sum of its binary digits is even.

The product of its digits is 158723712, while the sum is 71.

The spelling of 661969893617 in words is "six hundred sixty-one billion, nine hundred sixty-nine million, eight hundred ninety-three thousand, six hundred seventeen".