661389618 has 8 divisors (see below), whose sum is σ = 1322779248. Its totient is φ = 220463204.

The previous prime is 661389571. The next prime is 661389667. The reversal of 661389618 is 816983166.

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

661389618 is an admirable number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55115796 + ... + 55115807.

It is an arithmetic number, because the mean of its divisors is an integer number (165347406).

Almost surely, 2^661389618 is an apocalyptic number.

661389618 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661389618 is a wasteful number, since it uses less digits than its factorization.

661389618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110231608.

The product of its digits is 373248, while the sum is 48.

The square root of 661389618 is about 25717.4963400406. The cubic root of 661389618 is about 871.2693928347.

The spelling of 661389618 in words is "six hundred sixty-one million, three hundred eighty-nine thousand, six hundred eighteen".