661615949 has 2 divisors, whose sum is σ = 661615950. Its totient is φ = 661615948.

The previous prime is 661615937. The next prime is 661616051. The reversal of 661615949 is 949516166.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 624100324 + 37515625 = 24982^2 + 6125^2 .

It is a cyclic number.

It is not a de Polignac number, because 661615949 - 2²⁸ = 393180493 is a prime.

It is a Chen prime.

It is equal to p_34365899 and since 661615949 and 34365899 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661615909) 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, 330807974 + 330807975.

It is an arithmetic number, because the mean of its divisors is an integer number (330807975).

Almost surely, 2^661615949 is an apocalyptic number.

It is an amenable number.

661615949 is a deficient number, since it is larger than the sum of its proper divisors (1).

661615949 is an equidigital number, since it uses as much as digits as its factorization.

661615949 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 349920, while the sum is 47.

The square root of 661615949 is about 25721.8962947913. The cubic root of 661615949 is about 871.3687658206.

The spelling of 661615949 in words is "six hundred sixty-one million, six hundred fifteen thousand, nine hundred forty-nine".