668997980 has 216 divisors, whose sum is σ = 1809634176. Its totient is φ = 206841600.

The previous prime is 668997947. The next prime is 668998003. The reversal of 668997980 is 89799866.

It is a Harshad number since it is a multiple of its sum of digits (62).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 10967150 + ... + 10967210.

It is an arithmetic number, because the mean of its divisors is an integer number (8377936).

Almost surely, 2^668997980 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 668997980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (904817088).

668997980 is an abundant number, since it is smaller than the sum of its proper divisors (1140636196).

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

668997980 is a wasteful number, since it uses less digits than its factorization.

668997980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153 (or 125 counting only the distinct ones).

The product of its (nonzero) digits is 11757312, while the sum is 62.

The square root of 668997980 is about 25864.9952638697. The cubic root of 668997980 is about 874.5975749473.

The spelling of 668997980 in words is "six hundred sixty-eight million, nine hundred ninety-seven thousand, nine hundred eighty".