821851 has 2 divisors, whose sum is σ = 821852. Its totient is φ = 821850.

The previous prime is 821833. The next prime is 821857. The reversal of 821851 is 158128.

821851 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 821851 - 2⁵ = 821819 is a prime.

It is not a weakly prime, because it can be changed into another prime (821857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410925 + 410926.

It is an arithmetic number, because the mean of its divisors is an integer number (410926).

2⁸²¹⁸⁵¹ is an apocalyptic number.

821851 is a deficient number, since it is larger than the sum of its proper divisors (1).

821851 is an equidigital number, since it uses as much as digits as its factorization.

821851 is an evil number, because the sum of its binary digits is even.

The product of its digits is 640, while the sum is 25.

The square root of 821851 is about 906.5599814684. The cubic root of 821851 is about 93.6693908578.

Adding to 821851 its reverse (158128), we get a palindrome (979979).

The spelling of 821851 in words is "eight hundred twenty-one thousand, eight hundred fifty-one".