42720561 has 16 divisors (see below), whose sum is σ = 68158720. Its totient is φ = 26289360.

The previous prime is 42720539. The next prime is 42720577. The reversal of 42720561 is 16502724.

It is not a de Polignac number, because 42720561 - 2⁵ = 42720529 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42720761) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 60505 + ... + 61206.

It is an arithmetic number, because the mean of its divisors is an integer number (4259920).

Almost surely, 2^42720561 is an apocalyptic number.

It is an amenable number.

42720561 is a deficient number, since it is larger than the sum of its proper divisors (25438159).

42720561 is a wasteful number, since it uses less digits than its factorization.

42720561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121733 (or 121727 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 27.

The square root of 42720561 is about 6536.0967710094. The cubic root of 42720561 is about 349.5792522296.

The spelling of 42720561 in words is "forty-two million, seven hundred twenty thousand, five hundred sixty-one".