661309507 has 2 divisors, whose sum is σ = 661309508. Its totient is φ = 661309506.

The previous prime is 661309487. The next prime is 661309511. The reversal of 661309507 is 705903166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661309507 - 2²⁷ = 527091779 is a prime.

It is not a weakly prime, because it can be changed into another prime (661309807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330654753 + 330654754.

It is an arithmetic number, because the mean of its divisors is an integer number (330654754).

Almost surely, 2^661309507 is an apocalyptic number.

661309507 is a deficient number, since it is larger than the sum of its proper divisors (1).

661309507 is an equidigital number, since it uses as much as digits as its factorization.

661309507 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34020, while the sum is 37.

The square root of 661309507 is about 25715.9387734533. The cubic root of 661309507 is about 871.2342138324.

The spelling of 661309507 in words is "six hundred sixty-one million, three hundred nine thousand, five hundred seven".