21512833 has 2 divisors, whose sum is σ = 21512834. Its totient is φ = 21512832.

The previous prime is 21512801. The next prime is 21512839. The reversal of 21512833 is 33821512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15000129 + 6512704 = 3873^2 + 2552^2 .

It is a cyclic number.

It is not a de Polignac number, because 21512833 - 2⁵ = 21512801 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21512798 and 21512807.

It is not a weakly prime, because it can be changed into another prime (21512839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10756416 + 10756417.

It is an arithmetic number, because the mean of its divisors is an integer number (10756417).

Almost surely, 2^21512833 is an apocalyptic number.

It is an amenable number.

21512833 is a deficient number, since it is larger than the sum of its proper divisors (1).

21512833 is an equidigital number, since it uses as much as digits as its factorization.

21512833 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1440, while the sum is 25.

The square root of 21512833 is about 4638.1928592934. The cubic root of 21512833 is about 278.1202014574.

The spelling of 21512833 in words is "twenty-one million, five hundred twelve thousand, eight hundred thirty-three".