1720561447 has 4 divisors (see below), whose sum is σ = 1876976136. Its totient is φ = 1564146760.

The previous prime is 1720561441. The next prime is 1720561471. The reversal of 1720561447 is 7441650271.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1720561447 - 2¹⁹ = 1720037159 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1720561441) 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, 78207328 + ... + 78207349.

It is an arithmetic number, because the mean of its divisors is an integer number (469244034).

Almost surely, 2^1720561447 is an apocalyptic number.

1720561447 is a deficient number, since it is larger than the sum of its proper divisors (156414689).

1720561447 is a wasteful number, since it uses less digits than its factorization.

1720561447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156414688.

The product of its (nonzero) digits is 47040, while the sum is 37.

The square root of 1720561447 is about 41479.6509990140. The cubic root of 1720561447 is about 1198.2756360592.

The spelling of 1720561447 in words is "one billion, seven hundred twenty million, five hundred sixty-one thousand, four hundred forty-seven".