31121311999 has 4 divisors (see below), whose sum is σ = 31142940480. Its totient is φ = 31099683520.

The previous prime is 31121311993. The next prime is 31121312003. The reversal of 31121311999 is 99911312113.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99911312113 = 3109 ⋅32136157.

It is a cyclic number.

It is not a de Polignac number, because 31121311999 - 2⁵ = 31121311967 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31121311993) 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, 10812082 + ... + 10814959.

It is an arithmetic number, because the mean of its divisors is an integer number (7785735120).

Almost surely, 2^31121311999 is an apocalyptic number.

31121311999 is a deficient number, since it is larger than the sum of its proper divisors (21628481).

31121311999 is a wasteful number, since it uses less digits than its factorization.

31121311999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21628480.

The product of its digits is 13122, while the sum is 40.

The spelling of 31121311999 in words is "thirty-one billion, one hundred twenty-one million, three hundred eleven thousand, nine hundred ninety-nine".