21908811 has 16 divisors (see below), whose sum is σ = 30700800. Its totient is φ = 13870560.

The previous prime is 21908797. The next prime is 21908827. The reversal of 21908811 is 11880912.

It is not a de Polignac number, because 21908811 - 2¹¹ = 21906763 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21908851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9216 + ... + 11346.

It is an arithmetic number, because the mean of its divisors is an integer number (1918800).

Almost surely, 2^21908811 is an apocalyptic number.

21908811 is a deficient number, since it is larger than the sum of its proper divisors (8791989).

21908811 is a wasteful number, since it uses less digits than its factorization.

21908811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2306.

The product of its (nonzero) digits is 1152, while the sum is 30.

The square root of 21908811 is about 4680.6848857833. The cubic root of 21908811 is about 279.8162527434.

The spelling of 21908811 in words is "twenty-one million, nine hundred eight thousand, eight hundred eleven".