72116521 has 4 divisors (see below), whose sum is σ = 72135252. Its totient is φ = 72097792.

The previous prime is 72116519. The next prime is 72116531. The reversal of 72116521 is 12561127.

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 14356521 + 57760000 = 3789^2 + 7600^2 .

It is a cyclic number.

It is not a de Polignac number, because 72116521 - 2¹ = 72116519 is a prime.

It is a super-2 number, since 2×72116521² = 10401585202286882, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72116501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1240 + ... + 12073.

It is an arithmetic number, because the mean of its divisors is an integer number (18033813).

Almost surely, 2^72116521 is an apocalyptic number.

It is an amenable number.

72116521 is a deficient number, since it is larger than the sum of its proper divisors (18731).

72116521 is a wasteful number, since it uses less digits than its factorization.

72116521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18730.

The product of its digits is 840, while the sum is 25.

The square root of 72116521 is about 8492.1446643354. The cubic root of 72116521 is about 416.2410635145.

Adding to 72116521 its reverse (12561127), we get a palindrome (84677648).

The spelling of 72116521 in words is "seventy-two million, one hundred sixteen thousand, five hundred twenty-one".