21403202221 has 4 divisors (see below), whose sum is σ = 21495061692. Its totient is φ = 21311342752.

The previous prime is 21403202209. The next prime is 21403202231. The reversal of 21403202221 is 12220230412.

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

It can be written as a sum of positive squares in 2 ways, for example, as 11054209321 + 10348992900 = 105139^2 + 101730^2 .

It is a cyclic number.

It is not a de Polignac number, because 21403202221 - 2¹⁵ = 21403169453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21403202231) 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, 45929386 + ... + 45929851.

It is an arithmetic number, because the mean of its divisors is an integer number (5373765423).

Almost surely, 2^21403202221 is an apocalyptic number.

It is an amenable number.

21403202221 is a deficient number, since it is larger than the sum of its proper divisors (91859471).

21403202221 is an equidigital number, since it uses as much as digits as its factorization.

21403202221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91859470.

The product of its (nonzero) digits is 384, while the sum is 19.

Adding to 21403202221 its reverse (12220230412), we get a palindrome (33623432633).

The spelling of 21403202221 in words is "twenty-one billion, four hundred three million, two hundred two thousand, two hundred twenty-one".