661204593911531 has 2 divisors, whose sum is σ = 661204593911532. Its totient is φ = 661204593911530.

The previous prime is 661204593911473. The next prime is 661204593911539. The reversal of 661204593911531 is 135119395402166.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661204593911531 is a prime.

It is a super-2 number, since 2×661204593911531² (a number of 30 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (661204593911539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330602296955765 + 330602296955766.

It is an arithmetic number, because the mean of its divisors is an integer number (330602296955766).

Almost surely, 2^{661204593911531} is an apocalyptic number.

661204593911531 is a deficient number, since it is larger than the sum of its proper divisors (1).

661204593911531 is an equidigital number, since it uses as much as digits as its factorization.

661204593911531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5248800, while the sum is 56.

The spelling of 661204593911531 in words is "six hundred sixty-one trillion, two hundred four billion, five hundred ninety-three million, nine hundred eleven thousand, five hundred thirty-one".