216880561 has 4 divisors (see below), whose sum is σ = 218799972. Its totient is φ = 214961152.

The previous prime is 216880523. The next prime is 216880571. The reversal of 216880561 is 165088612.

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 97634161 + 119246400 = 9881^2 + 10920^2 .

It is a cyclic number.

It is not a de Polignac number, because 216880561 - 2¹⁵ = 216847793 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 216880561.

It is not an unprimeable number, because it can be changed into a prime (216880511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 959536 + ... + 959761.

It is an arithmetic number, because the mean of its divisors is an integer number (54699993).

Almost surely, 2^216880561 is an apocalyptic number.

It is an amenable number.

216880561 is a deficient number, since it is larger than the sum of its proper divisors (1919411).

216880561 is a wasteful number, since it uses less digits than its factorization.

216880561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1919410.

The product of its (nonzero) digits is 23040, while the sum is 37.

The square root of 216880561 is about 14726.8652808396. The cubic root of 216880561 is about 600.8142288118.

The spelling of 216880561 in words is "two hundred sixteen million, eight hundred eighty thousand, five hundred sixty-one".