71031721 has 8 divisors (see below), whose sum is σ = 72902088. Its totient is φ = 69168000.

The previous prime is 71031707. The next prime is 71031731. The reversal of 71031721 is 12713017.

It can be written as a sum of positive squares in 4 ways, for example, as 13104400 + 57927321 = 3620^2 + 7611^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 71031721 - 2¹⁷ = 70900649 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 71031692 and 71031701.

It is not an unprimeable number, because it can be changed into a prime (71031731) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25791 + ... + 28411.

It is an arithmetic number, because the mean of its divisors is an integer number (9112761).

Almost surely, 2^71031721 is an apocalyptic number.

It is an amenable number.

71031721 is a deficient number, since it is larger than the sum of its proper divisors (1870367).

71031721 is a wasteful number, since it uses less digits than its factorization.

71031721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3323.

The product of its (nonzero) digits is 294, while the sum is 22.

The square root of 71031721 is about 8428.0318580319. The cubic root of 71031721 is about 414.1434328405.

Adding to 71031721 its reverse (12713017), we get a palindrome (83744738).

The spelling of 71031721 in words is "seventy-one million, thirty-one thousand, seven hundred twenty-one".