21803481 has 30 divisors (see below), whose sum is σ = 36777130. Its totient is φ = 12446784.

The previous prime is 21803479. The next prime is 21803521. The reversal of 21803481 is 18430812.

21803481 is a `hidden beast` number, since 2 + 180 + 3 + 481 = 666.

It can be written as a sum of positive squares in only one way, i.e., 16941456 + 4862025 = 4116^2 + 2205^2 .

It is not a de Polignac number, because 21803481 - 2¹ = 21803479 is a prime.

It is a super-2 number, since 2×21803481² = 950783567434722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21803081) 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 29 ways as a sum of consecutive naturals, for example, 21105 + ... + 22113.

Almost surely, 2^21803481 is an apocalyptic number.

21803481 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21803481 is a deficient number, since it is larger than the sum of its proper divisors (14973649).

21803481 is an equidigital number, since it uses as much as digits as its factorization.

21803481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1043 (or 1019 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 21803481 is about 4669.4197712350. The cubic root of 21803481 is about 279.3671122197.

The spelling of 21803481 in words is "twenty-one million, eight hundred three thousand, four hundred eighty-one".