990668221 has 4 divisors (see below), whose sum is σ = 990761472. Its totient is φ = 990574972.

The previous prime is 990668219. The next prime is 990668269. The reversal of 990668221 is 122866099.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 990668221 - 2¹ = 990668219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (990668291) 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, 28285 + ... + 52738.

It is an arithmetic number, because the mean of its divisors is an integer number (247690368).

Almost surely, 2^990668221 is an apocalyptic number.

It is an amenable number.

990668221 is a deficient number, since it is larger than the sum of its proper divisors (93251).

990668221 is a wasteful number, since it uses less digits than its factorization.

990668221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93250.

The product of its (nonzero) digits is 93312, while the sum is 43.

The square root of 990668221 is about 31474.8823826238. The cubic root of 990668221 is about 996.8796807346.

The spelling of 990668221 in words is "nine hundred ninety million, six hundred sixty-eight thousand, two hundred twenty-one".