21544493 has 2 divisors, whose sum is σ = 21544494. Its totient is φ = 21544492.

The previous prime is 21544487. The next prime is 21544513. The reversal of 21544493 is 39444512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20775364 + 769129 = 4558^2 + 877^2 .

It is a cyclic number.

It is not a de Polignac number, because 21544493 - 2²⁴ = 4767277 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21544403) 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, 10772246 + 10772247.

It is an arithmetic number, because the mean of its divisors is an integer number (10772247).

Almost surely, 2^21544493 is an apocalyptic number.

It is an amenable number.

21544493 is a deficient number, since it is larger than the sum of its proper divisors (1).

21544493 is an equidigital number, since it uses as much as digits as its factorization.

21544493 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17280, while the sum is 32.

The square root of 21544493 is about 4641.6045716972. The cubic root of 21544493 is about 278.2565692026.

The spelling of 21544493 in words is "twenty-one million, five hundred forty-four thousand, four hundred ninety-three".