990928921 has 2 divisors, whose sum is σ = 990928922. Its totient is φ = 990928920.

The previous prime is 990928901. The next prime is 990928943. The reversal of 990928921 is 129829099.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 905107225 + 85821696 = 30085^2 + 9264^2 .

It is a cyclic number.

It is not a de Polignac number, because 990928921 - 2¹⁷ = 990797849 is a prime.

It is not a weakly prime, because it can be changed into another prime (990928901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495464460 + 495464461.

It is an arithmetic number, because the mean of its divisors is an integer number (495464461).

Almost surely, 2^990928921 is an apocalyptic number.

It is an amenable number.

990928921 is a deficient number, since it is larger than the sum of its proper divisors (1).

990928921 is an equidigital number, since it uses as much as digits as its factorization.

990928921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 209952, while the sum is 49.

The square root of 990928921 is about 31479.0235077265. The cubic root of 990928921 is about 996.9671179255.

The spelling of 990928921 in words is "nine hundred ninety million, nine hundred twenty-eight thousand, nine hundred twenty-one".