21082861 has 2 divisors, whose sum is σ = 21082862. Its totient is φ = 21082860.

The previous prime is 21082849. The next prime is 21082871. The reversal of 21082861 is 16828012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12638025 + 8444836 = 3555^2 + 2906^2 .

It is a cyclic number.

It is not a de Polignac number, because 21082861 - 2⁵ = 21082829 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 (21082801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10541430 + 10541431.

It is an arithmetic number, because the mean of its divisors is an integer number (10541431).

Almost surely, 2^21082861 is an apocalyptic number.

It is an amenable number.

21082861 is a deficient number, since it is larger than the sum of its proper divisors (1).

21082861 is an equidigital number, since it uses as much as digits as its factorization.

21082861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1536, while the sum is 28.

The square root of 21082861 is about 4591.6076705224. The cubic root of 21082861 is about 276.2548100143.

The spelling of 21082861 in words is "twenty-one million, eighty-two thousand, eight hundred sixty-one".