72105409 has 4 divisors (see below), whose sum is σ = 72190404. Its totient is φ = 72020416.

The previous prime is 72105401. The next prime is 72105419. The reversal of 72105409 is 90450127.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 64000000 + 8105409 = 8000^2 + 2847^2 .

It is a cyclic number.

It is not a de Polignac number, because 72105409 - 2³ = 72105401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72105401) 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, 41212 + ... + 42925.

It is an arithmetic number, because the mean of its divisors is an integer number (18047601).

Almost surely, 2^72105409 is an apocalyptic number.

It is an amenable number.

72105409 is a deficient number, since it is larger than the sum of its proper divisors (84995).

72105409 is an equidigital number, since it uses as much as digits as its factorization.

72105409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84994.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 72105409 is about 8491.4903874408. The cubic root of 72105409 is about 416.2196837242.

The spelling of 72105409 in words is "seventy-two million, one hundred five thousand, four hundred nine".