71561521 has 4 divisors (see below), whose sum is σ = 72423792. Its totient is φ = 70699252.

The previous prime is 71561519. The next prime is 71561527. The reversal of 71561521 is 12516517.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 71561521 - 2¹ = 71561519 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 71561521.

It is not an unprimeable number, because it can be changed into a prime (71561527) 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, 431011 + ... + 431176.

It is an arithmetic number, because the mean of its divisors is an integer number (18105948).

Almost surely, 2^71561521 is an apocalyptic number.

It is an amenable number.

71561521 is a deficient number, since it is larger than the sum of its proper divisors (862271).

71561521 is an equidigital number, since it uses as much as digits as its factorization.

71561521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 862270.

The product of its digits is 2100, while the sum is 28.

The square root of 71561521 is about 8459.4042934476. The cubic root of 71561521 is about 415.1705323247.

The spelling of 71561521 in words is "seventy-one million, five hundred sixty-one thousand, five hundred twenty-one".