31721320801 has 4 divisors (see below), whose sum is σ = 31882342932. Its totient is φ = 31560298672.

The previous prime is 31721320769. The next prime is 31721320817. The reversal of 31721320801 is 10802312713.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 10802312713 = 53 ⋅203817221.

It can be written as a sum of positive squares in 2 ways, for example, as 29878851025 + 1842469776 = 172855^2 + 42924^2 .

It is a cyclic number.

It is not a de Polignac number, because 31721320801 - 2⁵ = 31721320769 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31721320801.

It is not an unprimeable number, because it can be changed into a prime (31721320831) 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, 80510770 + ... + 80511163.

It is an arithmetic number, because the mean of its divisors is an integer number (7970585733).

Almost surely, 2^31721320801 is an apocalyptic number.

It is an amenable number.

31721320801 is a deficient number, since it is larger than the sum of its proper divisors (161022131).

31721320801 is a wasteful number, since it uses less digits than its factorization.

31721320801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161022130.

The product of its (nonzero) digits is 2016, while the sum is 28.

The spelling of 31721320801 in words is "thirty-one billion, seven hundred twenty-one million, three hundred twenty thousand, eight hundred one".