668191220 has 24 divisors (see below), whose sum is σ = 1405417608. Its totient is φ = 266854400.

The previous prime is 668191219. The next prime is 668191241. The reversal of 668191220 is 22191866.

It can be written as a sum of positive squares in 4 ways, for example, as 262893796 + 405297424 = 16214^2 + 20132^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13241 + ... + 38880.

It is an arithmetic number, because the mean of its divisors is an integer number (58559067).

Almost surely, 2^668191220 is an apocalyptic number.

It is an amenable number.

668191220 is an abundant number, since it is smaller than the sum of its proper divisors (737226388).

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

668191220 is a wasteful number, since it uses less digits than its factorization.

668191220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52771 (or 52769 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 668191220 is about 25849.3949639058. The cubic root of 668191220 is about 874.2458677773.

The spelling of 668191220 in words is "six hundred sixty-eight million, one hundred ninety-one thousand, two hundred twenty".