9913921 has 2 divisors, whose sum is σ = 9913922. Its totient is φ = 9913920.

The previous prime is 9913919. The next prime is 9913931. The reversal of 9913921 is 1293199.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8473921 + 1440000 = 2911^2 + 1200^2 .

It is an emirp because it is prime and its reverse (1293199) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9913921 - 2¹ = 9913919 is a prime.

Together with 9913919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (9913901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4956960 + 4956961.

It is an arithmetic number, because the mean of its divisors is an integer number (4956961).

Almost surely, 2^9913921 is an apocalyptic number.

It is an amenable number.

9913921 is a deficient number, since it is larger than the sum of its proper divisors (1).

9913921 is an equidigital number, since it uses as much as digits as its factorization.

9913921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4374, while the sum is 34.

The square root of 9913921 is about 3148.6379594993. The cubic root of 9913921 is about 214.8235148056.

The spelling of 9913921 in words is "nine million, nine hundred thirteen thousand, nine hundred twenty-one".