21355331431 has 16 divisors (see below), whose sum is σ = 25340912640. Its totient is φ = 17608116960.

The previous prime is 21355331423. The next prime is 21355331441. The reversal of 21355331431 is 13413355312.

It is a happy number.

It is not a de Polignac number, because 21355331431 - 2³ = 21355331423 is a prime.

It is a super-2 number, since 2×21355331431² (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 = 21355331393 and 21355331402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21355331411) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 139081 + ... + 249106.

It is an arithmetic number, because the mean of its divisors is an integer number (1583807040).

Almost surely, 2^21355331431 is an apocalyptic number.

21355331431 is a deficient number, since it is larger than the sum of its proper divisors (3985581209).

21355331431 is a wasteful number, since it uses less digits than its factorization.

21355331431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 388494.

The product of its digits is 16200, while the sum is 31.

Adding to 21355331431 its reverse (13413355312), we get a palindrome (34768686743).

The spelling of 21355331431 in words is "twenty-one billion, three hundred fifty-five million, three hundred thirty-one thousand, four hundred thirty-one".