661974869 has 2 divisors, whose sum is σ = 661974870. Its totient is φ = 661974868.

The previous prime is 661974827. The next prime is 661974913. The reversal of 661974869 is 968479166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 614544100 + 47430769 = 24790^2 + 6887^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661974869 is a prime.

It is a super-2 number, since 2×661974869² = 876421454375134322, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661904869) 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, 330987434 + 330987435.

It is an arithmetic number, because the mean of its divisors is an integer number (330987435).

Almost surely, 2^661974869 is an apocalyptic number.

It is an amenable number.

661974869 is a deficient number, since it is larger than the sum of its proper divisors (1).

661974869 is an equidigital number, since it uses as much as digits as its factorization.

661974869 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3919104, while the sum is 56.

The square root of 661974869 is about 25728.8722838759. The cubic root of 661974869 is about 871.5263069339.

The spelling of 661974869 in words is "six hundred sixty-one million, nine hundred seventy-four thousand, eight hundred sixty-nine".