21255743 has 2 divisors, whose sum is σ = 21255744. Its totient is φ = 21255742.

The previous prime is 21255733. The next prime is 21255757. The reversal of 21255743 is 34755212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21255743 - 2⁴ = 21255727 is a prime.

It is a super-2 number, since 2×21255743² = 903613220964098, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21255733) 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, 10627871 + 10627872.

It is an arithmetic number, because the mean of its divisors is an integer number (10627872).

Almost surely, 2^21255743 is an apocalyptic number.

21255743 is a deficient number, since it is larger than the sum of its proper divisors (1).

21255743 is an equidigital number, since it uses as much as digits as its factorization.

21255743 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8400, while the sum is 29.

The square root of 21255743 is about 4610.3951023746. The cubic root of 21255743 is about 277.0078629489.

It can be divided in two parts, 212 and 55743, that added together give a palindrome (55955).

The spelling of 21255743 in words is "twenty-one million, two hundred fifty-five thousand, seven hundred forty-three".