661552361 has 2 divisors, whose sum is σ = 661552362. Its totient is φ = 661552360.

The previous prime is 661552349. The next prime is 661552363. The reversal of 661552361 is 163255166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 576912361 + 84640000 = 24019^2 + 9200^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661552361 is a prime.

Together with 661552363, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (661552363) 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, 330776180 + 330776181.

It is an arithmetic number, because the mean of its divisors is an integer number (330776181).

Almost surely, 2^661552361 is an apocalyptic number.

It is an amenable number.

661552361 is a deficient number, since it is larger than the sum of its proper divisors (1).

661552361 is an equidigital number, since it uses as much as digits as its factorization.

661552361 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32400, while the sum is 35.

The square root of 661552361 is about 25720.6601975921. The cubic root of 661552361 is about 871.3408491355.

The spelling of 661552361 in words is "six hundred sixty-one million, five hundred fifty-two thousand, three hundred sixty-one".