21856733 has 2 divisors, whose sum is σ = 21856734. Its totient is φ = 21856732.

The previous prime is 21856697. The next prime is 21856741. The reversal of 21856733 is 33765812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21187609 + 669124 = 4603^2 + 818^2 .

It is a cyclic number.

It is not a de Polignac number, because 21856733 - 2¹⁰ = 21855709 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21856693 and 21856702.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21856763) 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 as a sum of consecutive naturals, namely, 10928366 + 10928367.

It is an arithmetic number, because the mean of its divisors is an integer number (10928367).

Almost surely, 2^21856733 is an apocalyptic number.

It is an amenable number.

21856733 is a deficient number, since it is larger than the sum of its proper divisors (1).

21856733 is an equidigital number, since it uses as much as digits as its factorization.

21856733 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 35.

The square root of 21856733 is about 4675.1185011719. The cubic root of 21856733 is about 279.5943658756.

The spelling of 21856733 in words is "twenty-one million, eight hundred fifty-six thousand, seven hundred thirty-three".