21321733 has 2 divisors, whose sum is σ = 21321734. Its totient is φ = 21321732.

The previous prime is 21321709. The next prime is 21321749. The reversal of 21321733 is 33712312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11068929 + 10252804 = 3327^2 + 3202^2 .

It is a cyclic number.

It is not a de Polignac number, because 21321733 - 2¹³ = 21313541 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21321133) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660866 + 10660867.

It is an arithmetic number, because the mean of its divisors is an integer number (10660867).

Almost surely, 2^21321733 is an apocalyptic number.

It is an amenable number.

21321733 is a deficient number, since it is larger than the sum of its proper divisors (1).

21321733 is an equidigital number, since it uses as much as digits as its factorization.

21321733 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 756, while the sum is 22.

The square root of 21321733 is about 4617.5462098392. The cubic root of 21321733 is about 277.2942304889.

The spelling of 21321733 in words is "twenty-one million, three hundred twenty-one thousand, seven hundred thirty-three".