21681803 has 32 divisors (see below), whose sum is σ = 27052032. Its totient is φ = 17107200.

The previous prime is 21681799. The next prime is 21681833. The reversal of 21681803 is 30818612.

It is not a de Polignac number, because 21681803 - 2² = 21681799 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21681833) 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 31 ways as a sum of consecutive naturals, for example, 296975 + ... + 297047.

It is an arithmetic number, because the mean of its divisors is an integer number (845376).

Almost surely, 2^21681803 is an apocalyptic number.

21681803 is a deficient number, since it is larger than the sum of its proper divisors (5370229).

21681803 is a wasteful number, since it uses less digits than its factorization.

21681803 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 21681803 is about 4656.3723004073. The cubic root of 21681803 is about 278.8464573985.

The spelling of 21681803 in words is "twenty-one million, six hundred eighty-one thousand, eight hundred three".