661911583 has 2 divisors, whose sum is σ = 661911584. Its totient is φ = 661911582.

The previous prime is 661911557. The next prime is 661911589. The reversal of 661911583 is 385119166.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661911583 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661911589) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330955791 + 330955792.

It is an arithmetic number, because the mean of its divisors is an integer number (330955792).

Almost surely, 2^661911583 is an apocalyptic number.

661911583 is a deficient number, since it is larger than the sum of its proper divisors (1).

661911583 is an equidigital number, since it uses as much as digits as its factorization.

661911583 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 40.

The square root of 661911583 is about 25727.6423910159. The cubic root of 661911583 is about 871.4985328827.

The spelling of 661911583 in words is "six hundred sixty-one million, nine hundred eleven thousand, five hundred eighty-three".