9921409 has 2 divisors, whose sum is σ = 9921410. Its totient is φ = 9921408.

The previous prime is 9921407. The next prime is 9921449. The reversal of 9921409 is 9041299.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6235009 + 3686400 = 2497^2 + 1920^2 .

It is a cyclic number.

It is not a de Polignac number, because 9921409 - 2¹ = 9921407 is a prime.

Together with 9921407, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (9921407) 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, 4960704 + 4960705.

It is an arithmetic number, because the mean of its divisors is an integer number (4960705).

Almost surely, 2^9921409 is an apocalyptic number.

It is an amenable number.

9921409 is a deficient number, since it is larger than the sum of its proper divisors (1).

9921409 is an equidigital number, since it uses as much as digits as its factorization.

9921409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 9921409 is about 3149.8268206363. The cubic root of 9921409 is about 214.8775867063.

It can be divided in two parts, 992 and 1409, that added together give a 4-th power (2401 = 7⁴).

The spelling of 9921409 in words is "nine million, nine hundred twenty-one thousand, four hundred nine".