216720261522 has 54 divisors (see below), whose sum is σ = 472970029077. Its totient is φ = 71719322832.

The previous prime is 216720261521. The next prime is 216720261557. The reversal of 216720261522 is 225162027612.

216720261522 is a `hidden beast` number, since 2 + 1 + 6 + 72 + 0 + 2 + 61 + 522 = 666.

216720261522 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 120713858721 + 96006402801 = 347439^2 + 309849^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=329181.

It is not an unprimeable number, because it can be changed into a prime (216720261521) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 353540088 + ... + 353540700.

Almost surely, 2^216720261522 is an apocalyptic number.

216720261522 is an abundant number, since it is smaller than the sum of its proper divisors (256249767555).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

216720261522 is an frugal number, since it uses more digits than its factorization.

216720261522 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1592 (or 797 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The spelling of 216720261522 in words is "two hundred sixteen billion, seven hundred twenty million, two hundred sixty-one thousand, five hundred twenty-two".