21131431331 has 4 divisors (see below), whose sum is σ = 21249484200. Its totient is φ = 21013378464.

The previous prime is 21131431319. The next prime is 21131431337. The reversal of 21131431331 is 13313413112.

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 21131431331 - 2¹⁴ = 21131414947 is a prime.

It is a super-2 number, since 2×21131431331² (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 = 21131431297 and 21131431306.

It is not an unprimeable number, because it can be changed into a prime (21131431337) 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, 59026166 + ... + 59026523.

It is an arithmetic number, because the mean of its divisors is an integer number (5312371050).

Almost surely, 2^21131431331 is an apocalyptic number.

21131431331 is a deficient number, since it is larger than the sum of its proper divisors (118052869).

21131431331 is a wasteful number, since it uses less digits than its factorization.

21131431331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 118052868.

The product of its digits is 648, while the sum is 23.

Adding to 21131431331 its reverse (13313413112), we get a palindrome (34444844443).

The spelling of 21131431331 in words is "twenty-one billion, one hundred thirty-one million, four hundred thirty-one thousand, three hundred thirty-one".