668100921 has 4 divisors (see below), whose sum is σ = 890801232. Its totient is φ = 445400612.

The previous prime is 668100919. The next prime is 668100949. The reversal of 668100921 is 129001866.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 668100921 - 2¹ = 668100919 is a prime.

It is not an unprimeable number, because it can be changed into a prime (668100991) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111350151 + ... + 111350156.

It is an arithmetic number, because the mean of its divisors is an integer number (222700308).

Almost surely, 2^668100921 is an apocalyptic number.

It is an amenable number.

668100921 is a deficient number, since it is larger than the sum of its proper divisors (222700311).

668100921 is a wasteful number, since it uses less digits than its factorization.

668100921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222700310.

The product of its (nonzero) digits is 5184, while the sum is 33.

The square root of 668100921 is about 25847.6482682661. The cubic root of 668100921 is about 874.2064842986.

The spelling of 668100921 in words is "six hundred sixty-eight million, one hundred thousand, nine hundred twenty-one".