31123121 has 4 divisors (see below), whose sum is σ = 32761200. Its totient is φ = 29485044.

The previous prime is 31123109. The next prime is 31123123. The reversal of 31123121 is 12132113.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12132113 = 7 ⋅1733159.

It is a cyclic number.

It is not a de Polignac number, because 31123121 - 2²² = 26928817 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31123096 and 31123105.

It is not an unprimeable number, because it can be changed into a prime (31123123) 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, 819011 + ... + 819048.

It is an arithmetic number, because the mean of its divisors is an integer number (8190300).

Almost surely, 2^31123121 is an apocalyptic number.

It is an amenable number.

31123121 is a deficient number, since it is larger than the sum of its proper divisors (1638079).

31123121 is a wasteful number, since it uses less digits than its factorization.

31123121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1638078.

The product of its digits is 36, while the sum is 14.

The square root of 31123121 is about 5578.8099985570. The cubic root of 31123121 is about 314.5533975149.

Adding to 31123121 its reverse (12132113), we get a palindrome (43255234).

It can be divided in two parts, 311 and 23121, that added together give a palindrome (23432).

The spelling of 31123121 in words is "thirty-one million, one hundred twenty-three thousand, one hundred twenty-one".