21312833 has 2 divisors, whose sum is σ = 21312834. Its totient is φ = 21312832.

The previous prime is 21312829. The next prime is 21312871. The reversal of 21312833 is 33821312.

21312833 is nontrivially palindromic in base 16.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16507969 + 4804864 = 4063^2 + 2192^2 .

It is a cyclic number.

It is not a de Polignac number, because 21312833 - 2² = 21312829 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21312799 and 21312808.

It is not a weakly prime, because it can be changed into another prime (21312233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656416 + 10656417.

It is an arithmetic number, because the mean of its divisors is an integer number (10656417).

Almost surely, 2^21312833 is an apocalyptic number.

It is an amenable number.

21312833 is a deficient number, since it is larger than the sum of its proper divisors (1).

21312833 is an equidigital number, since it uses as much as digits as its factorization.

21312833 is an evil number, because the sum of its binary digits is even.

The product of its digits is 864, while the sum is 23.

The square root of 21312833 is about 4616.5823939360. The cubic root of 21312833 is about 277.2556429108.

The spelling of 21312833 in words is "twenty-one million, three hundred twelve thousand, eight hundred thirty-three".