9931921 has 2 divisors, whose sum is σ = 9931922. Its totient is φ = 9931920.

The previous prime is 9931913. The next prime is 9931951. The reversal of 9931921 is 1291399.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5475600 + 4456321 = 2340^2 + 2111^2 .

It is a cyclic number.

It is not a de Polignac number, because 9931921 - 2³ = 9931913 is a prime.

9931921 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (9931951) 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, 4965960 + 4965961.

It is an arithmetic number, because the mean of its divisors is an integer number (4965961).

Almost surely, 2^9931921 is an apocalyptic number.

It is an amenable number.

9931921 is a deficient number, since it is larger than the sum of its proper divisors (1).

9931921 is an equidigital number, since it uses as much as digits as its factorization.

9931921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4374, while the sum is 34.

The square root of 9931921 is about 3151.4950420396. The cubic root of 9931921 is about 214.9534494495.

The spelling of 9931921 in words is "nine million, nine hundred thirty-one thousand, nine hundred twenty-one".