21804535 has 4 divisors (see below), whose sum is σ = 26165448. Its totient is φ = 17443624.

The previous prime is 21804499. The next prime is 21804539. The reversal of 21804535 is 53540812.

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 21804535 - 2¹³ = 21796343 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21804539) 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, 2180449 + ... + 2180458.

It is an arithmetic number, because the mean of its divisors is an integer number (6541362).

Almost surely, 2^21804535 is an apocalyptic number.

21804535 is a deficient number, since it is larger than the sum of its proper divisors (4360913).

21804535 is an equidigital number, since it uses as much as digits as its factorization.

21804535 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4360912.

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 21804535 is about 4669.5326318594. The cubic root of 21804535 is about 279.3716137668.

The spelling of 21804535 in words is "twenty-one million, eight hundred four thousand, five hundred thirty-five".