661974913 has 2 divisors, whose sum is σ = 661974914. Its totient is φ = 661974912.

The previous prime is 661974869. The next prime is 661974919. The reversal of 661974913 is 319479166.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 552626064 + 109348849 = 23508^2 + 10457^2 .

It is a cyclic number.

It is not a de Polignac number, because 661974913 - 2²¹ = 659877761 is a prime.

It is not a weakly prime, because it can be changed into another prime (661974919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330987456 + 330987457.

It is an arithmetic number, because the mean of its divisors is an integer number (330987457).

Almost surely, 2^661974913 is an apocalyptic number.

It is an amenable number.

661974913 is a deficient number, since it is larger than the sum of its proper divisors (1).

661974913 is an equidigital number, since it uses as much as digits as its factorization.

661974913 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 244944, while the sum is 46.

The square root of 661974913 is about 25728.8731389464. The cubic root of 661974913 is about 871.5263262433.

The spelling of 661974913 in words is "six hundred sixty-one million, nine hundred seventy-four thousand, nine hundred thirteen".