21420313231 has 4 divisors (see below), whose sum is σ = 21420765352. Its totient is φ = 21419861112.

The previous prime is 21420313223. The next prime is 21420313237. The reversal of 21420313231 is 13231302412.

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 21420313231 - 2³ = 21420313223 is a prime.

It is a super-2 number, since 2×21420313231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420313237) 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, 145401 + ... + 252946.

It is an arithmetic number, because the mean of its divisors is an integer number (5355191338).

Almost surely, 2^21420313231 is an apocalyptic number.

21420313231 is a deficient number, since it is larger than the sum of its proper divisors (452121).

21420313231 is an equidigital number, since it uses as much as digits as its factorization.

21420313231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 452120.

The product of its (nonzero) digits is 864, while the sum is 22.

Adding to 21420313231 its reverse (13231302412), we get a palindrome (34651615643).

The spelling of 21420313231 in words is "twenty-one billion, four hundred twenty million, three hundred thirteen thousand, two hundred thirty-one".