9921021 has 16 divisors (see below), whose sum is σ = 15191040. Its totient is φ = 5695920.

The previous prime is 9921019. The next prime is 9921053. The reversal of 9921021 is 1201299.

It is not a de Polignac number, because 9921021 - 2¹ = 9921019 is a prime.

9921021 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 9920982 and 9921000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9921001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7285 + ... + 8538.

It is an arithmetic number, because the mean of its divisors is an integer number (949440).

Almost surely, 2^9921021 is an apocalyptic number.

It is an amenable number.

9921021 is a deficient number, since it is larger than the sum of its proper divisors (5270019).

9921021 is a wasteful number, since it uses less digits than its factorization.

9921021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15856.

The product of its (nonzero) digits is 324, while the sum is 24.

The square root of 9921021 is about 3149.7652293465. The cubic root of 9921021 is about 214.8747855723.

The spelling of 9921021 in words is "nine million, nine hundred twenty-one thousand, twenty-one".