21543345 has 12 divisors (see below), whose sum is σ = 37341876. Its totient is φ = 11489760.

The previous prime is 21543331. The next prime is 21543371. The reversal of 21543345 is 54334512.

It can be written as a sum of positive squares in 2 ways, for example, as 4004001 + 17539344 = 2001^2 + 4188^2 .

It is not a de Polignac number, because 21543345 - 2⁷ = 21543217 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 239326 + ... + 239415.

It is an arithmetic number, because the mean of its divisors is an integer number (3111823).

Almost surely, 2^21543345 is an apocalyptic number.

It is an amenable number.

21543345 is a deficient number, since it is larger than the sum of its proper divisors (15798531).

21543345 is a wasteful number, since it uses less digits than its factorization.

21543345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 478752 (or 478749 counting only the distinct ones).

The product of its digits is 7200, while the sum is 27.

The square root of 21543345 is about 4641.4809059179. The cubic root of 21543345 is about 278.2516268071.

Adding to 21543345 its reverse (54334512), we get a palindrome (75877857).

The spelling of 21543345 in words is "twenty-one million, five hundred forty-three thousand, three hundred forty-five".