31420721771 has 4 divisors (see below), whose sum is σ = 32013565632. Its totient is φ = 30827877912.

The previous prime is 31420721749. The next prime is 31420721791. The reversal of 31420721771 is 17712702413.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31420721771 is a prime.

It is a super-2 number, since 2×31420721771² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31420721711) 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, 296421851 + ... + 296421956.

It is an arithmetic number, because the mean of its divisors is an integer number (8003391408).

Almost surely, 2^31420721771 is an apocalyptic number.

31420721771 is a deficient number, since it is larger than the sum of its proper divisors (592843861).

31420721771 is an equidigital number, since it uses as much as digits as its factorization.

31420721771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 592843860.

The product of its (nonzero) digits is 16464, while the sum is 35.

The spelling of 31420721771 in words is "thirty-one billion, four hundred twenty million, seven hundred twenty-one thousand, seven hundred seventy-one".