21818833 has 2 divisors, whose sum is σ = 21818834. Its totient is φ = 21818832.

The previous prime is 21818809. The next prime is 21818851. The reversal of 21818833 is 33881812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12159169 + 9659664 = 3487^2 + 3108^2 .

It is a cyclic number.

It is not a de Polignac number, because 21818833 - 2⁵ = 21818801 is a prime.

It is a super-2 number, since 2×21818833² = 952122946963778, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21818873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10909416 + 10909417.

It is an arithmetic number, because the mean of its divisors is an integer number (10909417).

Almost surely, 2^21818833 is an apocalyptic number.

It is an amenable number.

21818833 is a deficient number, since it is larger than the sum of its proper divisors (1).

21818833 is an equidigital number, since it uses as much as digits as its factorization.

21818833 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9216, while the sum is 34.

The square root of 21818833 is about 4671.0633692983. The cubic root of 21818833 is about 279.4326650198.

The spelling of 21818833 in words is "twenty-one million, eight hundred eighteen thousand, eight hundred thirty-three".