21845539 has 4 divisors (see below), whose sum is σ = 21886024. Its totient is φ = 21805056.

The previous prime is 21845533. The next prime is 21845543. The reversal of 21845539 is 93554812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21845539 - 2³ = 21845531 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21845498 and 21845507.

It is not an unprimeable number, because it can be changed into a prime (21845531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19422 + ... + 20515.

It is an arithmetic number, because the mean of its divisors is an integer number (5471506).

Almost surely, 2^21845539 is an apocalyptic number.

21845539 is a deficient number, since it is larger than the sum of its proper divisors (40485).

21845539 is an equidigital number, since it uses as much as digits as its factorization.

21845539 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40484.

The product of its digits is 43200, while the sum is 37.

The square root of 21845539 is about 4673.9211589414. The cubic root of 21845539 is about 279.5466259901.

The spelling of 21845539 in words is "twenty-one million, eight hundred forty-five thousand, five hundred thirty-nine".