72161865 has 12 divisors (see below), whose sum is σ = 125080644. Its totient is φ = 38486304.

The previous prime is 72161849. The next prime is 72161891. The reversal of 72161865 is 56816127.

It can be written as a sum of positive squares in 2 ways, for example, as 56385081 + 15776784 = 7509^2 + 3972^2 .

It is not a de Polignac number, because 72161865 - 2⁴ = 72161849 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 801754 + ... + 801843.

It is an arithmetic number, because the mean of its divisors is an integer number (10423387).

Almost surely, 2^72161865 is an apocalyptic number.

It is an amenable number.

72161865 is a deficient number, since it is larger than the sum of its proper divisors (52918779).

72161865 is a wasteful number, since it uses less digits than its factorization.

72161865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1603608 (or 1603605 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 72161865 is about 8494.8140062040. The cubic root of 72161865 is about 416.3282838451.

The spelling of 72161865 in words is "seventy-two million, one hundred sixty-one thousand, eight hundred sixty-five".