31420721791 has 2 divisors, whose sum is σ = 31420721792. Its totient is φ = 31420721790.

The previous prime is 31420721749. The next prime is 31420721803. The reversal of 31420721791 is 19712702413.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 31420721791 - 2⁷ = 31420721663 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31420721791.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31420721711) 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 as a sum of consecutive naturals, namely, 15710360895 + 15710360896.

It is an arithmetic number, because the mean of its divisors is an integer number (15710360896).

Almost surely, 2^31420721791 is an apocalyptic number.

31420721791 is a deficient number, since it is larger than the sum of its proper divisors (1).

31420721791 is an equidigital number, since it uses as much as digits as its factorization.

31420721791 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 21168, while the sum is 37.

The spelling of 31420721791 in words is "thirty-one billion, four hundred twenty million, seven hundred twenty-one thousand, seven hundred ninety-one".