31651913991491 has 4 divisors (see below), whose sum is σ = 31787759116152. Its totient is φ = 31516068866832.

The previous prime is 31651913991473. The next prime is 31651913991499. The reversal of 31651913991491 is 19419931915613.

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 31651913991491 - 2¹⁰ = 31651913990467 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31651913991499) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67922561981 + ... + 67922562446.

It is an arithmetic number, because the mean of its divisors is an integer number (7946939779038).

Almost surely, 2^{31651913991491} is an apocalyptic number.

31651913991491 is a deficient number, since it is larger than the sum of its proper divisors (135845124661).

31651913991491 is a wasteful number, since it uses less digits than its factorization.

31651913991491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135845124660.

The product of its digits is 7085880, while the sum is 62.

The spelling of 31651913991491 in words is "thirty-one trillion, six hundred fifty-one billion, nine hundred thirteen million, nine hundred ninety-one thousand, four hundred ninety-one".