31131010781 has 4 divisors (see below), whose sum is σ = 33525703932. Its totient is φ = 28736317632.

The previous prime is 31131010697. The next prime is 31131010783. The reversal of 31131010781 is 18701013113.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8658302500 + 22472708281 = 93050^2 + 149909^2 .

It is a cyclic number.

It is not a de Polignac number, because 31131010781 - 2¹⁰ = 31131009757 is a prime.

It is a super-2 number, since 2×31131010781² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31131010781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31131010783) 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, 1197346556 + ... + 1197346581.

It is an arithmetic number, because the mean of its divisors is an integer number (8381425983).

Almost surely, 2^31131010781 is an apocalyptic number.

It is an amenable number.

31131010781 is a deficient number, since it is larger than the sum of its proper divisors (2394693151).

31131010781 is a wasteful number, since it uses less digits than its factorization.

31131010781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2394693150.

The product of its (nonzero) digits is 504, while the sum is 26.

Adding to 31131010781 its reverse (18701013113), we get a palindrome (49832023894).

The spelling of 31131010781 in words is "thirty-one billion, one hundred thirty-one million, ten thousand, seven hundred eighty-one".