72315621 has 18 divisors (see below), whose sum is σ = 121510662. Its totient is φ = 41322960.

The previous prime is 72315619. The next prime is 72315641. The reversal of 72315621 is 12651327.

It is a happy number.

72315621 is a `hidden beast` number, since 7 + 2 + 31 + 5 + 621 = 666.

It can be written as a sum of positive squares in only one way, i.e., 67076100 + 5239521 = 8190^2 + 2289^2 .

It is not a de Polignac number, because 72315621 - 2¹ = 72315619 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72315641) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 81550 + ... + 82431.

Almost surely, 2^72315621 is an apocalyptic number.

It is an amenable number.

72315621 is a deficient number, since it is larger than the sum of its proper divisors (49195041).

72315621 is a wasteful number, since it uses less digits than its factorization.

72315621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164001 (or 163991 counting only the distinct ones).

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

The square root of 72315621 is about 8503.8591827476. The cubic root of 72315621 is about 416.6237656807.

Adding to 72315621 its reverse (12651327), we get a palindrome (84966948).

The spelling of 72315621 in words is "seventy-two million, three hundred fifteen thousand, six hundred twenty-one".