21820833 has 10 divisors (see below), whose sum is σ = 32596674. Its totient is φ = 14547168.

The previous prime is 21820811. The next prime is 21820837. The reversal of 21820833 is 33802812.

It can be written as a sum of positive squares in only one way, i.e., 20493729 + 1327104 = 4527^2 + 1152^2 .

It is not a de Polignac number, because 21820833 - 2⁶ = 21820769 is a prime.

It is a super-2 number, since 2×21820833² = 952297505627778, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21820797 and 21820806.

It is not an unprimeable number, because it can be changed into a prime (21820837) 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 in 9 ways as a sum of consecutive naturals, for example, 134616 + ... + 134777.

Almost surely, 2^21820833 is an apocalyptic number.

It is an amenable number.

21820833 is a deficient number, since it is larger than the sum of its proper divisors (10775841).

21820833 is an equidigital number, since it uses as much as digits as its factorization.

21820833 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 269405 (or 269396 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 21820833 is about 4671.2774484074. The cubic root of 21820833 is about 279.4412027245.

The spelling of 21820833 in words is "twenty-one million, eight hundred twenty thousand, eight hundred thirty-three".