71991000281 has 4 divisors (see below), whose sum is σ = 72703782564. Its totient is φ = 71278218000.

The previous prime is 71991000269. The next prime is 71991000299. The reversal of 71991000281 is 18200019917.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18200019917 = 101 ⋅180198217.

It can be written as a sum of positive squares in 2 ways, for example, as 45992662681 + 25998337600 = 214459^2 + 161240^2 .

It is a cyclic number.

It is not a de Polignac number, because 71991000281 - 2⁶ = 71991000217 is a prime.

It is a super-2 number, since 2×71991000281² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71991000181) 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, 356390990 + ... + 356391191.

It is an arithmetic number, because the mean of its divisors is an integer number (18175945641).

Almost surely, 2^71991000281 is an apocalyptic number.

71991000281 is the 119993-rd centered decagonal number.

It is an amenable number.

71991000281 is a deficient number, since it is larger than the sum of its proper divisors (712782283).

71991000281 is a wasteful number, since it uses less digits than its factorization.

71991000281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 712782282.

The product of its (nonzero) digits is 9072, while the sum is 38.

The spelling of 71991000281 in words is "seventy-one billion, nine hundred ninety-one million, two hundred eighty-one", and thus it is an aban number.