661917070643 has 2 divisors, whose sum is σ = 661917070644. Its totient is φ = 661917070642.

The previous prime is 661917070637. The next prime is 661917070651. The reversal of 661917070643 is 346070719166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661917070643 - 2¹⁶ = 661917005107 is a prime.

It is a super-2 number, since 2×661917070643² (a number of 24 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 661917070591 and 661917070600.

It is not a weakly prime, because it can be changed into another prime (661917070613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330958535321 + 330958535322.

It is an arithmetic number, because the mean of its divisors is an integer number (330958535322).

Almost surely, 2^661917070643 is an apocalyptic number.

661917070643 is a deficient number, since it is larger than the sum of its proper divisors (1).

661917070643 is an equidigital number, since it uses as much as digits as its factorization.

661917070643 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1143072, while the sum is 50.

The spelling of 661917070643 in words is "six hundred sixty-one billion, nine hundred seventeen million, seventy thousand, six hundred forty-three".