71533738721 has 4 divisors (see below), whose sum is σ = 71602988292. Its totient is φ = 71464489152.

The previous prime is 71533738709. The next prime is 71533738733. The reversal of 71533738721 is 12783733517.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12783733517 = 7237 ⋅1766441.

It is an interprime number because it is at equal distance from previous prime (71533738709) and next prime (71533738733).

It can be written as a sum of positive squares in 2 ways, for example, as 33600723025 + 37933015696 = 183305^2 + 194764^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71533738721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71533738751) 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, 34623236 + ... + 34625301.

It is an arithmetic number, because the mean of its divisors is an integer number (17900747073).

Almost surely, 2^71533738721 is an apocalyptic number.

It is an amenable number.

71533738721 is a deficient number, since it is larger than the sum of its proper divisors (69249571).

71533738721 is a wasteful number, since it uses less digits than its factorization.

71533738721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69249570.

The product of its digits is 740880, while the sum is 47.

The spelling of 71533738721 in words is "seventy-one billion, five hundred thirty-three million, seven hundred thirty-eight thousand, seven hundred twenty-one".