21851833 has 2 divisors, whose sum is σ = 21851834. Its totient is φ = 21851832.

The previous prime is 21851813. The next prime is 21851839. The reversal of 21851833 is 33815812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13307904 + 8543929 = 3648^2 + 2923^2 .

It is a cyclic number.

It is not a de Polignac number, because 21851833 - 2²¹ = 19754681 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21851795 and 21851804.

It is not a weakly prime, because it can be changed into another prime (21851839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10925916 + 10925917.

It is an arithmetic number, because the mean of its divisors is an integer number (10925917).

Almost surely, 2^21851833 is an apocalyptic number.

It is an amenable number.

21851833 is a deficient number, since it is larger than the sum of its proper divisors (1).

21851833 is an equidigital number, since it uses as much as digits as its factorization.

21851833 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5760, while the sum is 31.

The square root of 21851833 is about 4674.5944209097. The cubic root of 21851833 is about 279.5734704871.

The spelling of 21851833 in words is "twenty-one million, eight hundred fifty-one thousand, eight hundred thirty-three".