72138445 has 8 divisors (see below), whose sum is σ = 87006744. Its totient is φ = 57417024.

The previous prime is 72138439. The next prime is 72138449. The reversal of 72138445 is 54483127.

72138445 = 216² + 217² + ... + 609².

It can be written as a sum of positive squares in 4 ways, for example, as 25270729 + 46867716 = 5027^2 + 6846^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 72138445 - 2¹¹ = 72136397 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 72138445.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72138449) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35634 + ... + 37603.

It is an arithmetic number, because the mean of its divisors is an integer number (10875843).

Almost surely, 2^72138445 is an apocalyptic number.

It is an amenable number.

72138445 is a deficient number, since it is larger than the sum of its proper divisors (14868299).

72138445 is a wasteful number, since it uses less digits than its factorization.

72138445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73439.

The product of its digits is 26880, while the sum is 34.

The square root of 72138445 is about 8493.4354062417. The cubic root of 72138445 is about 416.2832394466.

The spelling of 72138445 in words is "seventy-two million, one hundred thirty-eight thousand, four hundred forty-five".