21820303 has 4 divisors (see below), whose sum is σ = 22968760. Its totient is φ = 20671848.

The previous prime is 21820301. The next prime is 21820319. The reversal of 21820303 is 30302812.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21820303 - 2¹ = 21820301 is a prime.

It is a super-2 number, since 2×21820303² = 952251246023618, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (19), and also a Moran number because the ratio is a prime number: 1148437 = 21820303 / (2 + 1 + 8 + 2 + 0 + 3 + 0 + 3).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21820301) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 574200 + ... + 574237.

It is an arithmetic number, because the mean of its divisors is an integer number (5742190).

Almost surely, 2^21820303 is an apocalyptic number.

21820303 is a deficient number, since it is larger than the sum of its proper divisors (1148457).

21820303 is a wasteful number, since it uses less digits than its factorization.

21820303 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1148456.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21820303 is about 4671.2207183990. The cubic root of 21820303 is about 279.4389402835.

The spelling of 21820303 in words is "twenty-one million, eight hundred twenty thousand, three hundred three".