71720561 has 8 divisors (see below), whose sum is σ = 79120800. Its totient is φ = 64467040.

The previous prime is 71720557. The next prime is 71720581. The reversal of 71720561 is 16502717.

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

It is not a de Polignac number, because 71720561 - 2² = 71720557 is a prime.

It is not an unprimeable number, because it can be changed into a prime (71720531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35651 + ... + 37608.

It is an arithmetic number, because the mean of its divisors is an integer number (9890100).

Almost surely, 2^71720561 is an apocalyptic number.

It is an amenable number.

71720561 is a deficient number, since it is larger than the sum of its proper divisors (7400239).

71720561 is a wasteful number, since it uses less digits than its factorization.

71720561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73359.

The product of its (nonzero) digits is 2940, while the sum is 29.

The square root of 71720561 is about 8468.7992655394. The cubic root of 71720561 is about 415.4778663325.

The spelling of 71720561 in words is "seventy-one million, seven hundred twenty thousand, five hundred sixty-one".