21131211421 has 4 divisors (see below), whose sum is σ = 21580811712. Its totient is φ = 20681611132.

The previous prime is 21131211419. The next prime is 21131211443. The reversal of 21131211421 is 12411213112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21131211421 - 2¹ = 21131211419 is a prime.

It is a super-2 number, since 2×21131211421² (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 (21131211121) 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, 224800075 + ... + 224800168.

It is an arithmetic number, because the mean of its divisors is an integer number (5395202928).

Almost surely, 2^21131211421 is an apocalyptic number.

It is an amenable number.

21131211421 is a deficient number, since it is larger than the sum of its proper divisors (449600291).

21131211421 is an equidigital number, since it uses as much as digits as its factorization.

21131211421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 449600290.

The product of its digits is 96, while the sum is 19.

Adding to 21131211421 its reverse (12411213112), we get a palindrome (33542424533).

The spelling of 21131211421 in words is "twenty-one billion, one hundred thirty-one million, two hundred eleven thousand, four hundred twenty-one".