720640181 has 4 divisors (see below), whose sum is σ = 722957664. Its totient is φ = 718322700.

The previous prime is 720640147. The next prime is 720640187. The reversal of 720640181 is 181046027.

720640181 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 720640181 - 2²⁶ = 653531317 is a prime.

It is a super-2 number, since 2×720640181² = 1038644540943425522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (720640187) 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, 1158275 + ... + 1158896.

It is an arithmetic number, because the mean of its divisors is an integer number (180739416).

Almost surely, 2^720640181 is an apocalyptic number.

It is an amenable number.

720640181 is a deficient number, since it is larger than the sum of its proper divisors (2317483).

720640181 is a wasteful number, since it uses less digits than its factorization.

720640181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2317482.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 720640181 is about 26844.7421481377. The cubic root of 720640181 is about 896.5465104507.

The spelling of 720640181 in words is "seven hundred twenty million, six hundred forty thousand, one hundred eighty-one".