669331921 has 2 divisors, whose sum is σ = 669331922. Its totient is φ = 669331920.

The previous prime is 669331891. The next prime is 669331967. The reversal of 669331921 is 129133966.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 491242896 + 178089025 = 22164^2 + 13345^2 .

It is a cyclic number.

It is not a de Polignac number, because 669331921 - 2⁵ = 669331889 is a prime.

It is not a weakly prime, because it can be changed into another prime (669331991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334665960 + 334665961.

It is an arithmetic number, because the mean of its divisors is an integer number (334665961).

Almost surely, 2^669331921 is an apocalyptic number.

It is an amenable number.

669331921 is a deficient number, since it is larger than the sum of its proper divisors (1).

669331921 is an equidigital number, since it uses as much as digits as its factorization.

669331921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 52488, while the sum is 40.

The square root of 669331921 is about 25871.4499207138. The cubic root of 669331921 is about 874.7430738451.

The spelling of 669331921 in words is "six hundred sixty-nine million, three hundred thirty-one thousand, nine hundred twenty-one".