661986674 has 4 divisors (see below), whose sum is σ = 992980014. Its totient is φ = 330993336.

The previous prime is 661986671. The next prime is 661986691. The reversal of 661986674 is 476689166.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 624250225 + 37736449 = 24985^2 + 6143^2 .

It is not an unprimeable number, because it can be changed into a prime (661986671) 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, 165496667 + ... + 165496670.

Almost surely, 2^661986674 is an apocalyptic number.

661986674 is a deficient number, since it is larger than the sum of its proper divisors (330993340).

661986674 is a wasteful number, since it uses less digits than its factorization.

661986674 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330993339.

The product of its digits is 2612736, while the sum is 53.

The square root of 661986674 is about 25729.1016943849. The cubic root of 661986674 is about 871.5314875469.

The spelling of 661986674 in words is "six hundred sixty-one million, nine hundred eighty-six thousand, six hundred seventy-four".