21800811 has 8 divisors (see below), whose sum is σ = 29128000. Its totient is φ = 14503752.

The previous prime is 21800797. The next prime is 21800819. The reversal of 21800811 is 11800812.

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

It is not a de Polignac number, because 21800811 - 2⁶ = 21800747 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21800819) 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, 5785 + ... + 8778.

It is an arithmetic number, because the mean of its divisors is an integer number (3641000).

Almost surely, 2^21800811 is an apocalyptic number.

21800811 is a deficient number, since it is larger than the sum of its proper divisors (7327189).

21800811 is a wasteful number, since it uses less digits than its factorization.

21800811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15065.

The product of its (nonzero) digits is 128, while the sum is 21.

The square root of 21800811 is about 4669.1338597217. The cubic root of 21800811 is about 279.3557082205.

Subtracting from 21800811 its reverse (11800812), we obtain a palindrome (9999999).

The spelling of 21800811 in words is "twenty-one million, eight hundred thousand, eight hundred eleven".