220215661 has 4 divisors (see below), whose sum is σ = 227319424. Its totient is φ = 213111900.

The previous prime is 220215649. The next prime is 220215691. The reversal of 220215661 is 166512022.

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 not a de Polignac number, because 220215661 - 2⁵ = 220215629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (220215691) 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, 3551835 + ... + 3551896.

It is an arithmetic number, because the mean of its divisors is an integer number (56829856).

Almost surely, 2^220215661 is an apocalyptic number.

220215661 is the 6637-th centered decagonal number.

It is an amenable number.

220215661 is a deficient number, since it is larger than the sum of its proper divisors (7103763).

220215661 is an equidigital number, since it uses as much as digits as its factorization.

220215661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7103762.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 220215661 is about 14839.6651242540. The cubic root of 220215661 is about 603.8782675377.

Adding to 220215661 its reverse (166512022), we get a palindrome (386727683).

The spelling of 220215661 in words is "two hundred twenty million, two hundred fifteen thousand, six hundred sixty-one".