21805801 has 8 divisors (see below), whose sum is σ = 22140000. Its totient is φ = 21473760.

The previous prime is 21805783. The next prime is 21805807. The reversal of 21805801 is 10850812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21805801 - 2⁵ = 21805769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21805807) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 43450 + ... + 43948.

It is an arithmetic number, because the mean of its divisors is an integer number (2767500).

Almost surely, 2^21805801 is an apocalyptic number.

It is an amenable number.

21805801 is a deficient number, since it is larger than the sum of its proper divisors (334199).

21805801 is an equidigital number, since it uses as much as digits as its factorization.

21805801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1079.

The product of its (nonzero) digits is 640, while the sum is 25.

The square root of 21805801 is about 4669.6681894970. The cubic root of 21805801 is about 279.3770205567.

The spelling of 21805801 in words is "twenty-one million, eight hundred five thousand, eight hundred one".