821971 has 2 divisors, whose sum is σ = 821972. Its totient is φ = 821970.

The previous prime is 821941. The next prime is 821993. The reversal of 821971 is 179128.

821971 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 821971 - 2⁵ = 821939 is a prime.

It is not a weakly prime, because it can be changed into another prime (821911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410985 + 410986.

It is an arithmetic number, because the mean of its divisors is an integer number (410986).

2⁸²¹⁹⁷¹ is an apocalyptic number.

821971 is a deficient number, since it is larger than the sum of its proper divisors (1).

821971 is an equidigital number, since it uses as much as digits as its factorization.

821971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008, while the sum is 28.

The square root of 821971 is about 906.6261633110. The cubic root of 821971 is about 93.6739495835.

The spelling of 821971 in words is "eight hundred twenty-one thousand, nine hundred seventy-one".