21803881 has 16 divisors (see below), whose sum is σ = 25141248. Its totient is φ = 18723600.

The previous prime is 21803879. The next prime is 21803891. The reversal of 21803881 is 18830812.

It is a cyclic number.

It is not a de Polignac number, because 21803881 - 2¹ = 21803879 is a prime.

It is a super-3 number, since 3×21803881³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is not an unprimeable number, because it can be changed into a prime (21803801) 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, 13920 + ... + 15406.

It is an arithmetic number, because the mean of its divisors is an integer number (1571328).

Almost surely, 2^21803881 is an apocalyptic number.

It is an amenable number.

21803881 is a deficient number, since it is larger than the sum of its proper divisors (3337367).

21803881 is a wasteful number, since it uses less digits than its factorization.

21803881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1572.

The product of its (nonzero) digits is 3072, while the sum is 31.

The square root of 21803881 is about 4669.4626029127. The cubic root of 21803881 is about 279.3688206038.

The spelling of 21803881 in words is "twenty-one million, eight hundred three thousand, eight hundred eighty-one".