20831861 has 2 divisors, whose sum is σ = 20831862. Its totient is φ = 20831860.

The previous prime is 20831849. The next prime is 20831869. The reversal of 20831861 is 16813802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11771761 + 9060100 = 3431^2 + 3010^2 .

It is a cyclic number.

It is not a de Polignac number, because 20831861 - 2¹⁰ = 20830837 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 (20831869) by changing a digit.

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

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10415930 + 10415931.

It is an arithmetic number, because the mean of its divisors is an integer number (10415931).

Almost surely, 2^20831861 is an apocalyptic number.

It is an amenable number.

20831861 is a deficient number, since it is larger than the sum of its proper divisors (1).

20831861 is an equidigital number, since it uses as much as digits as its factorization.

20831861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 20831861 is about 4564.1933569909. The cubic root of 20831861 is about 275.1541218718.

The spelling of 20831861 in words is "twenty million, eight hundred thirty-one thousand, eight hundred sixty-one".