21255733 has 2 divisors, whose sum is σ = 21255734. Its totient is φ = 21255732.

The previous prime is 21255727. The next prime is 21255743. The reversal of 21255733 is 33755212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14691889 + 6563844 = 3833^2 + 2562^2 .

It is a cyclic number.

It is not a de Polignac number, because 21255733 - 2¹⁷ = 21124661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21255743) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627866 + 10627867.

It is an arithmetic number, because the mean of its divisors is an integer number (10627867).

Almost surely, 2^21255733 is an apocalyptic number.

It is an amenable number.

21255733 is a deficient number, since it is larger than the sum of its proper divisors (1).

21255733 is an equidigital number, since it uses as much as digits as its factorization.

21255733 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6300, while the sum is 28.

The square root of 21255733 is about 4610.3940178688. The cubic root of 21255733 is about 277.0078195084.

It can be divided in two parts, 212 and 55733, that added together give a triangular number (55945 = T₃₃₄).

The spelling of 21255733 in words is "twenty-one million, two hundred fifty-five thousand, seven hundred thirty-three".