7857139 has 4 divisors (see below), whose sum is σ = 7864056. Its totient is φ = 7850224.

The previous prime is 7857137. The next prime is 7857163. The reversal of 7857139 is 9317587.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 9317587 = 139 ⋅67033.

It is a cyclic number.

It is not a de Polignac number, because 7857139 - 2¹ = 7857137 is a prime.

It is a Duffinian number.

7857139 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (7857137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1309 + ... + 4174.

It is an arithmetic number, because the mean of its divisors is an integer number (1966014).

Almost surely, 2^7857139 is an apocalyptic number.

7857139 is a deficient number, since it is larger than the sum of its proper divisors (6917).

7857139 is a wasteful number, since it uses less digits than its factorization.

7857139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6916.

The product of its digits is 52920, while the sum is 40.

The square root of 7857139 is about 2803.0588648831. The cubic root of 7857139 is about 198.8023339631.

The spelling of 7857139 in words is "seven million, eight hundred fifty-seven thousand, one hundred thirty-nine".