660121668 has 18 divisors (see below), whose sum is σ = 1668640974. Its totient is φ = 220040544.

The previous prime is 660121667. The next prime is 660121669. The reversal of 660121668 is 866121066.

It is an interprime number because it is at equal distance from previous prime (660121667) and next prime (660121669).

It can be written as a sum of positive squares in only one way, i.e., 512207424 + 147914244 = 22632^2 + 12162^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 18336713 = 660121668 / (6 + 6 + 0 + 1 + 2 + 1 + 6 + 6 + 8).

It is not an unprimeable number, because it can be changed into a prime (660121667) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 9168321 + ... + 9168392.

Almost surely, 2^660121668 is an apocalyptic number.

It is an amenable number.

660121668 is an abundant number, since it is smaller than the sum of its proper divisors (1008519306).

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

660121668 is a wasteful number, since it uses less digits than its factorization.

660121668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18336723 (or 18336718 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 660121668 is about 25692.8330084481. The cubic root of 660121668 is about 870.7122664923.

The spelling of 660121668 in words is "six hundred sixty million, one hundred twenty-one thousand, six hundred sixty-eight".