216422561 has 4 divisors (see below), whose sum is σ = 220090800. Its totient is φ = 212754324.

The previous prime is 216422543. The next prime is 216422573. The reversal of 216422561 is 165224612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216422561 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (216424561) 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 3 ways as a sum of consecutive naturals, for example, 1834031 + ... + 1834148.

It is an arithmetic number, because the mean of its divisors is an integer number (55022700).

Almost surely, 2^216422561 is an apocalyptic number.

It is an amenable number.

216422561 is a deficient number, since it is larger than the sum of its proper divisors (3668239).

216422561 is an equidigital number, since it uses as much as digits as its factorization.

216422561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3668238.

The product of its digits is 5760, while the sum is 29.

The square root of 216422561 is about 14711.3072498674. The cubic root of 216422561 is about 600.3910053212.

The spelling of 216422561 in words is "two hundred sixteen million, four hundred twenty-two thousand, five hundred sixty-one".