72345121 has 4 divisors (see below), whose sum is σ = 72362644. Its totient is φ = 72327600.

The previous prime is 72345113. The next prime is 72345181. The reversal of 72345121 is 12154327.

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 51322896 + 21022225 = 7164^2 + 4585^2 .

It is a cyclic number.

It is not a de Polignac number, because 72345121 - 2³ = 72345113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72345181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1231 + ... + 12091.

It is an arithmetic number, because the mean of its divisors is an integer number (18090661).

Almost surely, 2^72345121 is an apocalyptic number.

It is an amenable number.

72345121 is a deficient number, since it is larger than the sum of its proper divisors (17523).

72345121 is a wasteful number, since it uses less digits than its factorization.

72345121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17522.

The product of its digits is 1680, while the sum is 25.

The square root of 72345121 is about 8505.5935125069. The cubic root of 72345121 is about 416.6804096445.

Adding to 72345121 its reverse (12154327), we get a palindrome (84499448).

The spelling of 72345121 in words is "seventy-two million, three hundred forty-five thousand, one hundred twenty-one".