72135621 has 6 divisors (see below), whose sum is σ = 104195910. Its totient is φ = 48090408.

The previous prime is 72135601. The next prime is 72135629. The reversal of 72135621 is 12653127.

It is a happy number.

72135621 is a `hidden beast` number, since 7 + 2 + 1 + 35 + 621 = 666.

It can be written as a sum of positive squares in only one way, i.e., 60233121 + 11902500 = 7761^2 + 3450^2 .

It is not a de Polignac number, because 72135621 - 2⁷ = 72135493 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72135629) 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 5 ways as a sum of consecutive naturals, for example, 4007526 + ... + 4007543.

It is an arithmetic number, because the mean of its divisors is an integer number (17365985).

Almost surely, 2^72135621 is an apocalyptic number.

It is an amenable number.

72135621 is a deficient number, since it is larger than the sum of its proper divisors (32060289).

72135621 is a wasteful number, since it uses less digits than its factorization.

72135621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8015075 (or 8015072 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 72135621 is about 8493.2691585749. The cubic root of 72135621 is about 416.2778073028.

Adding to 72135621 its reverse (12653127), we get a palindrome (84788748).

The spelling of 72135621 in words is "seventy-two million, one hundred thirty-five thousand, six hundred twenty-one".