31123213121 has 32 divisors (see below), whose sum is σ = 42021504000. Its totient is φ = 22261135680.

The previous prime is 31123213091. The next prime is 31123213129. The reversal of 31123213121 is 12131232113.

It is a happy number.

It is not a de Polignac number, because 31123213121 - 2⁶ = 31123213057 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31123213093 and 31123213102.

It is not an unprimeable number, because it can be changed into a prime (31123213129) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 92330 + ... + 266028.

It is an arithmetic number, because the mean of its divisors is an integer number (1313172000).

Almost surely, 2^31123213121 is an apocalyptic number.

It is an amenable number.

31123213121 is a deficient number, since it is larger than the sum of its proper divisors (10898290879).

31123213121 is a wasteful number, since it uses less digits than its factorization.

31123213121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173909.

The product of its digits is 216, while the sum is 20.

Adding to 31123213121 its reverse (12131232113), we get a palindrome (43254445234).

The spelling of 31123213121 in words is "thirty-one billion, one hundred twenty-three million, two hundred thirteen thousand, one hundred twenty-one".