9913821 has 4 divisors (see below), whose sum is σ = 13218432. Its totient is φ = 6609212.

The previous prime is 9913811. The next prime is 9913837. The reversal of 9913821 is 1283199.

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: 1283199 = 3 ⋅427733.

It is a cyclic number.

It is not a de Polignac number, because 9913821 - 2¹¹ = 9911773 is a prime.

9913821 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9913811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1652301 + ... + 1652306.

It is an arithmetic number, because the mean of its divisors is an integer number (3304608).

Almost surely, 2^9913821 is an apocalyptic number.

It is an amenable number.

9913821 is a deficient number, since it is larger than the sum of its proper divisors (3304611).

9913821 is a wasteful number, since it uses less digits than its factorization.

9913821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3304610.

The product of its digits is 3888, while the sum is 33.

The square root of 9913821 is about 3148.6220795770. The cubic root of 9913821 is about 214.8227925073.

The spelling of 9913821 in words is "nine million, nine hundred thirteen thousand, eight hundred twenty-one".