7857121 has 4 divisors (see below), whose sum is σ = 7880112. Its totient is φ = 7834132.

The previous prime is 7857107. The next prime is 7857137. The reversal of 7857121 is 1217587.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7857121 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7851121) 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, 10975 + ... + 11668.

It is an arithmetic number, because the mean of its divisors is an integer number (1970028).

Almost surely, 2^7857121 is an apocalyptic number.

It is an amenable number.

7857121 is a deficient number, since it is larger than the sum of its proper divisors (22991).

7857121 is a wasteful number, since it uses less digits than its factorization.

7857121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22990.

The product of its digits is 3920, while the sum is 31.

The square root of 7857121 is about 2803.0556541032. The cubic root of 7857121 is about 198.8021821502.

The spelling of 7857121 in words is "seven million, eight hundred fifty-seven thousand, one hundred twenty-one".