21214244431 has 4 divisors (see below), whose sum is σ = 21303007200. Its totient is φ = 21125481664.

The previous prime is 21214244423. The next prime is 21214244449. The reversal of 21214244431 is 13444241212.

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 21214244431 - 2³ = 21214244423 is a prime.

It is a super-2 number, since 2×21214244431² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21214244431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21214244731) 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, 44381026 + ... + 44381503.

It is an arithmetic number, because the mean of its divisors is an integer number (5325751800).

Almost surely, 2^21214244431 is an apocalyptic number.

21214244431 is a deficient number, since it is larger than the sum of its proper divisors (88762769).

21214244431 is an equidigital number, since it uses as much as digits as its factorization.

21214244431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88762768.

The product of its digits is 6144, while the sum is 28.

Adding to 21214244431 its reverse (13444241212), we get a palindrome (34658485643).

The spelling of 21214244431 in words is "twenty-one billion, two hundred fourteen million, two hundred forty-four thousand, four hundred thirty-one".