31231311321020 has 144 divisors (see below), whose sum is σ = 70422481678752. Its totient is φ = 11630911488000.

The previous prime is 31231311321013. The next prime is 31231311321029. The reversal of 31231311321020 is 2012311313213.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31231311321029) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1287823895 + ... + 1287848145.

It is an arithmetic number, because the mean of its divisors is an integer number (489045011658).

Almost surely, 2^{31231311321020} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31231311321020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35211240839376).

31231311321020 is an abundant number, since it is smaller than the sum of its proper divisors (39191170357732).

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

31231311321020 is a wasteful number, since it uses less digits than its factorization.

31231311321020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26688 (or 26669 counting only the distinct ones).

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

Adding to 31231311321020 its reverse (2012311313213), we get a palindrome (33243622634233).

The spelling of 31231311321020 in words is "thirty-one trillion, two hundred thirty-one billion, three hundred eleven million, three hundred twenty-one thousand, twenty".