9921749 has 4 divisors (see below), whose sum is σ = 9939936. Its totient is φ = 9903564.

The previous prime is 9921733. The next prime is 9921797. The reversal of 9921749 is 9471299.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9471299 = 47 ⋅201517.

It is a cyclic number.

It is not a de Polignac number, because 9921749 - 2⁴ = 9921733 is a prime.

It is a super-2 number, since 2×9921749² = 196882206438002, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9921449) 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, 8249 + ... + 9374.

It is an arithmetic number, because the mean of its divisors is an integer number (2484984).

Almost surely, 2^9921749 is an apocalyptic number.

It is an amenable number.

9921749 is a deficient number, since it is larger than the sum of its proper divisors (18187).

9921749 is a wasteful number, since it uses less digits than its factorization.

9921749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18186.

The product of its digits is 40824, while the sum is 41.

The square root of 9921749 is about 3149.8807913951. The cubic root of 9921749 is about 214.8800412483.

The spelling of 9921749 in words is "nine million, nine hundred twenty-one thousand, seven hundred forty-nine".