71935720921 has 4 divisors (see below), whose sum is σ = 72073793844. Its totient is φ = 71797648000.

The previous prime is 71935720889. The next prime is 71935720931. The reversal of 71935720921 is 12902753917.

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

It can be written as a sum of positive squares in 2 ways, for example, as 35330465296 + 36605255625 = 187964^2 + 191325^2 .

It is a cyclic number.

It is not a de Polignac number, because 71935720921 - 2⁵ = 71935720889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71935720931) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 69035680 + ... + 69036721.

It is an arithmetic number, because the mean of its divisors is an integer number (18018448461).

Almost surely, 2^71935720921 is an apocalyptic number.

It is an amenable number.

71935720921 is a deficient number, since it is larger than the sum of its proper divisors (138072923).

71935720921 is a wasteful number, since it uses less digits than its factorization.

71935720921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138072922.

The product of its (nonzero) digits is 238140, while the sum is 46.

The spelling of 71935720921 in words is "seventy-one billion, nine hundred thirty-five million, seven hundred twenty thousand, nine hundred twenty-one".