661870905 has 8 divisors (see below), whose sum is σ = 1058993472. Its totient is φ = 352997808.

The previous prime is 661870841. The next prime is 661870939. The reversal of 661870905 is 509078166.

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

It is not a de Polignac number, because 661870905 - 2⁶ = 661870841 is a prime.

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 7 ways as a sum of consecutive naturals, for example, 22062349 + ... + 22062378.

It is an arithmetic number, because the mean of its divisors is an integer number (132374184).

Almost surely, 2^661870905 is an apocalyptic number.

It is an amenable number.

661870905 is a deficient number, since it is larger than the sum of its proper divisors (397122567).

661870905 is a wasteful number, since it uses less digits than its factorization.

661870905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44124735.

The product of its (nonzero) digits is 90720, while the sum is 42.

The square root of 661870905 is about 25726.8518283913. The cubic root of 661870905 is about 871.4806797714.

The spelling of 661870905 in words is "six hundred sixty-one million, eight hundred seventy thousand, nine hundred five".