661535756611 has 2 divisors, whose sum is σ = 661535756612. Its totient is φ = 661535756610.

The previous prime is 661535756587. The next prime is 661535756617. The reversal of 661535756611 is 116657535166.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661535756611 - 2⁵ = 661535756579 is a prime.

It is not a weakly prime, because it can be changed into another prime (661535756617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330767878305 + 330767878306.

It is an arithmetic number, because the mean of its divisors is an integer number (330767878306).

Almost surely, 2^661535756611 is an apocalyptic number.

661535756611 is a deficient number, since it is larger than the sum of its proper divisors (1).

661535756611 is an equidigital number, since it uses as much as digits as its factorization.

661535756611 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3402000, while the sum is 52.

The spelling of 661535756611 in words is "six hundred sixty-one billion, five hundred thirty-five million, seven hundred fifty-six thousand, six hundred eleven".