21131231310 has 96 divisors (see below), whose sum is σ = 63190176192. Its totient is φ = 4799208960.

The previous prime is 21131231309. The next prime is 21131231323. The reversal of 21131231310 is 1313213112.

21131231310 is a `hidden beast` number, since 2 + 11 + 312 + 31 + 310 = 666.

It is a super-2 number, since 2×21131231310² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 7911 + ... + 205730.

It is an arithmetic number, because the mean of its divisors is an integer number (658231002).

Almost surely, 2^21131231310 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21131231310, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31595088096).

21131231310 is an abundant number, since it is smaller than the sum of its proper divisors (42058944882).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21131231310 is a wasteful number, since it uses less digits than its factorization.

21131231310 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213818 (or 213815 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

Adding to 21131231310 its reverse (1313213112), we get a palindrome (22444444422).

The spelling of 21131231310 in words is "twenty-one billion, one hundred thirty-one million, two hundred thirty-one thousand, three hundred ten".