71381521 has 8 divisors (see below), whose sum is σ = 76134600. Its totient is φ = 66690048.

The previous prime is 71381509. The next prime is 71381617. The reversal of 71381521 is 12518317.

It can be written as a sum of positive squares in 4 ways, for example, as 4730625 + 66650896 = 2175^2 + 8164^2 .

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

It is not a de Polignac number, because 71381521 - 2²³ = 62992913 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 71381521.

It is not an unprimeable number, because it can be changed into a prime (71381021) 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, 12996 + ... + 17653.

It is an arithmetic number, because the mean of its divisors is an integer number (9516825).

Almost surely, 2^71381521 is an apocalyptic number.

It is an amenable number.

71381521 is a deficient number, since it is larger than the sum of its proper divisors (4753079).

71381521 is a wasteful number, since it uses less digits than its factorization.

71381521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30803.

The product of its digits is 1680, while the sum is 28.

The square root of 71381521 is about 8448.7585478578. The cubic root of 71381521 is about 414.8221447199.

Adding to 71381521 its reverse (12518317), we get a palindrome (83899838).

The spelling of 71381521 in words is "seventy-one million, three hundred eighty-one thousand, five hundred twenty-one".