668352021 has 4 divisors (see below), whose sum is σ = 891136032. Its totient is φ = 445568012.

The previous prime is 668352017. The next prime is 668352023. The reversal of 668352021 is 120253866.

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 668352021 - 2² = 668352017 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668352023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111392001 + ... + 111392006.

It is an arithmetic number, because the mean of its divisors is an integer number (222784008).

Almost surely, 2^668352021 is an apocalyptic number.

It is an amenable number.

668352021 is a deficient number, since it is larger than the sum of its proper divisors (222784011).

668352021 is a wasteful number, since it uses less digits than its factorization.

668352021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222784010.

The product of its (nonzero) digits is 17280, while the sum is 33.

The square root of 668352021 is about 25852.5051203940. The cubic root of 668352021 is about 874.3159915833.

The spelling of 668352021 in words is "six hundred sixty-eight million, three hundred fifty-two thousand, twenty-one".