6857621 has 2 divisors, whose sum is σ = 6857622. Its totient is φ = 6857620.

The previous prime is 6857593. The next prime is 6857639. The reversal of 6857621 is 1267586.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5827396 + 1030225 = 2414^2 + 1015^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6857621 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6857671) 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, 3428810 + 3428811.

It is an arithmetic number, because the mean of its divisors is an integer number (3428811).

Almost surely, 2^6857621 is an apocalyptic number.

It is an amenable number.

6857621 is a deficient number, since it is larger than the sum of its proper divisors (1).

6857621 is an equidigital number, since it uses as much as digits as its factorization.

6857621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 35.

The square root of 6857621 is about 2618.7059781503. The cubic root of 6857621 is about 189.9872659979.

Subtracting from 6857621 its sum of digits (35), we obtain a palindrome (6857586).

The spelling of 6857621 in words is "six million, eight hundred fifty-seven thousand, six hundred twenty-one".