31212999991 has 4 divisors (see below), whose sum is σ = 33049058832. Its totient is φ = 29376941152.

The previous prime is 31212999971. The next prime is 31213000031. The reversal of 31212999991 is 19999921213.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 31212999991 - 2⁹ = 31212999479 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 (31212999901) 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, 918029395 + ... + 918029428.

It is an arithmetic number, because the mean of its divisors is an integer number (8262264708).

Almost surely, 2^31212999991 is an apocalyptic number.

31212999991 is a deficient number, since it is larger than the sum of its proper divisors (1836058841).

31212999991 is a wasteful number, since it uses less digits than its factorization.

31212999991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1836058840.

The product of its digits is 708588, while the sum is 55.

The spelling of 31212999991 in words is "thirty-one billion, two hundred twelve million, nine hundred ninety-nine thousand, nine hundred ninety-one".