216221465 has 4 divisors (see below), whose sum is σ = 259465764. Its totient is φ = 172977168.

The previous prime is 216221461. The next prime is 216221519. The reversal of 216221465 is 564122612.

216221465 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 47844889 + 168376576 = 6917^2 + 12976^2 .

It is a cyclic number.

It is not a de Polignac number, because 216221465 - 2² = 216221461 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 (216221461) 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, 21622142 + ... + 21622151.

It is an arithmetic number, because the mean of its divisors is an integer number (64866441).

Almost surely, 2^216221465 is an apocalyptic number.

It is an amenable number.

216221465 is a deficient number, since it is larger than the sum of its proper divisors (43244299).

216221465 is an equidigital number, since it uses as much as digits as its factorization.

216221465 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43244298.

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

The square root of 216221465 is about 14704.4709187376. The cubic root of 216221465 is about 600.2049901423.

The spelling of 216221465 in words is "two hundred sixteen million, two hundred twenty-one thousand, four hundred sixty-five".