21131244331 has 4 divisors (see below), whose sum is σ = 21140795232. Its totient is φ = 21121693432.

The previous prime is 21131244287. The next prime is 21131244353. The reversal of 21131244331 is 13344213112.

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 21131244331 - 2¹⁷ = 21131113259 is a prime.

It is a super-2 number, since 2×21131244331² (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 = 21131244296 and 21131244305.

It is not an unprimeable number, because it can be changed into a prime (21131244931) 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, 4772131 + ... + 4776556.

It is an arithmetic number, because the mean of its divisors is an integer number (5285198808).

Almost surely, 2^21131244331 is an apocalyptic number.

21131244331 is a deficient number, since it is larger than the sum of its proper divisors (9550901).

21131244331 is an equidigital number, since it uses as much as digits as its factorization.

21131244331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9550900.

The product of its digits is 1728, while the sum is 25.

Adding to 21131244331 its reverse (13344213112), we get a palindrome (34475457443).

The spelling of 21131244331 in words is "twenty-one billion, one hundred thirty-one million, two hundred forty-four thousand, three hundred thirty-one".