21544373 has 2 divisors, whose sum is σ = 21544374. Its totient is φ = 21544372.

The previous prime is 21544363. The next prime is 21544403. The reversal of 21544373 is 37344512.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11444689 + 10099684 = 3383^2 + 3178^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21544373 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21544363) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772186 + 10772187.

It is an arithmetic number, because the mean of its divisors is an integer number (10772187).

Almost surely, 2^21544373 is an apocalyptic number.

It is an amenable number.

21544373 is a deficient number, since it is larger than the sum of its proper divisors (1).

21544373 is an equidigital number, since it uses as much as digits as its factorization.

21544373 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10080, while the sum is 29.

The square root of 21544373 is about 4641.5916451149. The cubic root of 21544373 is about 278.2560525841.

Adding to 21544373 its reverse (37344512), we get a palindrome (58888885).

The spelling of 21544373 in words is "twenty-one million, five hundred forty-four thousand, three hundred seventy-three".