31031100021 has 4 divisors (see below), whose sum is σ = 41374800032. Its totient is φ = 20687400012.

The previous prime is 31031100017. The next prime is 31031100043. The reversal of 31031100021 is 12000113013.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 31031100021 - 2² = 31031100017 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31031100011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5171850001 + ... + 5171850006.

It is an arithmetic number, because the mean of its divisors is an integer number (10343700008).

Almost surely, 2^31031100021 is an apocalyptic number.

It is an amenable number.

31031100021 is a deficient number, since it is larger than the sum of its proper divisors (10343700011).

31031100021 is a wasteful number, since it uses less digits than its factorization.

31031100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10343700010.

The product of its (nonzero) digits is 18, while the sum is 12.

Adding to 31031100021 its reverse (12000113013), we get a palindrome (43031213034).

The spelling of 31031100021 in words is "thirty-one billion, thirty-one million, one hundred thousand, twenty-one".