21809217403 has 4 divisors (see below), whose sum is σ = 21892142448. Its totient is φ = 21726292360.

The previous prime is 21809217361. The next prime is 21809217439. The reversal of 21809217403 is 30471290812.

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

It is a cyclic number.

It is not a de Polignac number, because 21809217403 - 2¹³ = 21809209211 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21809257403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41462128 + ... + 41462653.

It is an arithmetic number, because the mean of its divisors is an integer number (5473035612).

Almost surely, 2^21809217403 is an apocalyptic number.

21809217403 is a deficient number, since it is larger than the sum of its proper divisors (82925045).

21809217403 is an equidigital number, since it uses as much as digits as its factorization.

21809217403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82925044.

The product of its (nonzero) digits is 24192, while the sum is 37.

The spelling of 21809217403 in words is "twenty-one billion, eight hundred nine million, two hundred seventeen thousand, four hundred three".