21021304231 has 4 divisors (see below), whose sum is σ = 21031070112. Its totient is φ = 21011538352.

The previous prime is 21021304223. The next prime is 21021304237. The reversal of 21021304231 is 13240312012.

It is a happy number.

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 21021304231 - 2³ = 21021304223 is a prime.

It is a super-2 number, since 2×21021304231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21021304199 and 21021304208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021304237) 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, 4879711 + ... + 4884016.

It is an arithmetic number, because the mean of its divisors is an integer number (5257767528).

Almost surely, 2^21021304231 is an apocalyptic number.

21021304231 is a deficient number, since it is larger than the sum of its proper divisors (9765881).

21021304231 is an equidigital number, since it uses as much as digits as its factorization.

21021304231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9765880.

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

Adding to 21021304231 its reverse (13240312012), we get a palindrome (34261616243).

The spelling of 21021304231 in words is "twenty-one billion, twenty-one million, three hundred four thousand, two hundred thirty-one".