31123112221 has 4 divisors (see below), whose sum is σ = 31587636352. Its totient is φ = 30658588092.

The previous prime is 31123112183. The next prime is 31123112281. The reversal of 31123112221 is 12221132113.

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 a cyclic number.

It is not a de Polignac number, because 31123112221 - 2⁷ = 31123112093 is a prime.

It is a super-2 number, since 2×31123112221² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31123112281) 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, 232261965 + ... + 232262098.

It is an arithmetic number, because the mean of its divisors is an integer number (7896909088).

Almost surely, 2^31123112221 is an apocalyptic number.

It is an amenable number.

31123112221 is a deficient number, since it is larger than the sum of its proper divisors (464524131).

31123112221 is an equidigital number, since it uses as much as digits as its factorization.

31123112221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 464524130.

The product of its digits is 144, while the sum is 19.

Adding to 31123112221 its reverse (12221132113), we get a palindrome (43344244334).

The spelling of 31123112221 in words is "thirty-one billion, one hundred twenty-three million, one hundred twelve thousand, two hundred twenty-one".