661989166 has 8 divisors (see below), whose sum is σ = 993931704. Its totient is φ = 330678600.

The previous prime is 661989149. The next prime is 661989247.

661989166 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 155365 + ... + 159568.

It is an arithmetic number, because the mean of its divisors is an integer number (124241463).

Almost surely, 2^661989166 is an apocalyptic number.

661989166 is a deficient number, since it is larger than the sum of its proper divisors (331942538).

661989166 is a wasteful number, since it uses less digits than its factorization.

661989166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315986.

The product of its digits is 839808, while the sum is 52.

The square root of 661989166 is about 25729.1501219920. The cubic root of 661989166 is about 871.5325811509.

The spelling of 661989166 in words is "six hundred sixty-one million, nine hundred eighty-nine thousand, one hundred sixty-six".