21775243 has 16 divisors (see below), whose sum is σ = 25839616. Its totient is φ = 17962560.

The previous prime is 21775219. The next prime is 21775261. The reversal of 21775243 is 34257712.

It is not a de Polignac number, because 21775243 - 2¹⁷ = 21644171 is a prime.

It is a super-2 number, since 2×21775243² = 948322415418098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21776243) 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 in 15 ways as a sum of consecutive naturals, for example, 21478 + ... + 22468.

It is an arithmetic number, because the mean of its divisors is an integer number (1614976).

Almost surely, 2^21775243 is an apocalyptic number.

21775243 is a deficient number, since it is larger than the sum of its proper divisors (4064373).

21775243 is an equidigital number, since it uses as much as digits as its factorization.

21775243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1114.

The product of its digits is 11760, while the sum is 31.

The square root of 21775243 is about 4666.3950754303. The cubic root of 21775243 is about 279.2464560030.

The spelling of 21775243 in words is "twenty-one million, seven hundred seventy-five thousand, two hundred forty-three".