31197406991 has 4 divisors (see below), whose sum is σ = 32839375800. Its totient is φ = 29555438184.

The previous prime is 31197406927. The next prime is 31197407011. The reversal of 31197406991 is 19960479113.

It is a happy number.

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 31197406991 - 2⁶ = 31197406927 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31197406091) 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, 820984376 + ... + 820984413.

It is an arithmetic number, because the mean of its divisors is an integer number (8209843950).

Almost surely, 2^31197406991 is an apocalyptic number.

31197406991 is a deficient number, since it is larger than the sum of its proper divisors (1641968809).

31197406991 is a wasteful number, since it uses less digits than its factorization.

31197406991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1641968808.

The product of its (nonzero) digits is 367416, while the sum is 50.

The spelling of 31197406991 in words is "thirty-one billion, one hundred ninety-seven million, four hundred six thousand, nine hundred ninety-one".