661245839 has 2 divisors, whose sum is σ = 661245840. Its totient is φ = 661245838.

The previous prime is 661245817. The next prime is 661245853. The reversal of 661245839 is 938542166.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661245839 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 661245839.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661245859) 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, 330622919 + 330622920.

It is an arithmetic number, because the mean of its divisors is an integer number (330622920).

Almost surely, 2^661245839 is an apocalyptic number.

661245839 is a deficient number, since it is larger than the sum of its proper divisors (1).

661245839 is an equidigital number, since it uses as much as digits as its factorization.

661245839 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 311040, while the sum is 44.

The square root of 661245839 is about 25714.7008343477. The cubic root of 661245839 is about 871.2062533895.

The spelling of 661245839 in words is "six hundred sixty-one million, two hundred forty-five thousand, eight hundred thirty-nine".