9921421 has 4 divisors (see below), whose sum is σ = 10505052. Its totient is φ = 9337792.

The previous prime is 9921409. The next prime is 9921449. The reversal of 9921421 is 1241299.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1241299 = 389 ⋅3191.

It can be written as a sum of positive squares in 2 ways, for example, as 9084196 + 837225 = 3014^2 + 915^2 .

It is a cyclic number.

It is not a de Polignac number, because 9921421 - 2¹¹ = 9919373 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 9921421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9921491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 291790 + ... + 291823.

It is an arithmetic number, because the mean of its divisors is an integer number (2626263).

Almost surely, 2^9921421 is an apocalyptic number.

It is an amenable number.

9921421 is a deficient number, since it is larger than the sum of its proper divisors (583631).

9921421 is a wasteful number, since it uses less digits than its factorization.

9921421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 583630.

The product of its digits is 1296, while the sum is 28.

The square root of 9921421 is about 3149.8287255024. The cubic root of 9921421 is about 214.8776733382.

It can be divided in two parts, 99214 and 21, that added together give a triangular number (99235 = T₄₄₅).

The spelling of 9921421 in words is "nine million, nine hundred twenty-one thousand, four hundred twenty-one".