9139721 has 2 divisors, whose sum is σ = 9139722. Its totient is φ = 9139720.

The previous prime is 9139709. The next prime is 9139723. The reversal of 9139721 is 1279319.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9120400 + 19321 = 3020^2 + 139^2 .

It is an emirp because it is prime and its reverse (1279319) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9139721 - 2¹⁰ = 9138697 is a prime.

Together with 9139723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (9139723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4569860 + 4569861.

It is an arithmetic number, because the mean of its divisors is an integer number (4569861).

Almost surely, 2^9139721 is an apocalyptic number.

It is an amenable number.

9139721 is a deficient number, since it is larger than the sum of its proper divisors (1).

9139721 is an equidigital number, since it uses as much as digits as its factorization.

9139721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3402, while the sum is 32.

The square root of 9139721 is about 3023.1971487152. The cubic root of 9139721 is about 209.0792721426.

Subtracting from 9139721 its product of digits (3402), we obtain a palindrome (9136319).

The spelling of 9139721 in words is "nine million, one hundred thirty-nine thousand, seven hundred twenty-one".