220615661 has 4 divisors (see below), whose sum is σ = 252132192. Its totient is φ = 189099132.

The previous prime is 220615643. The next prime is 220615687. The reversal of 220615661 is 166516022.

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, and also an emirpimes, since its reverse is a distinct semiprime: 166516022 = 2 ⋅83258011.

It is a cyclic number.

It is not a de Polignac number, because 220615661 - 2¹⁸ = 220353517 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 (220615601) 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, 15758255 + ... + 15758268.

It is an arithmetic number, because the mean of its divisors is an integer number (63033048).

Almost surely, 2^220615661 is an apocalyptic number.

It is an amenable number.

220615661 is a deficient number, since it is larger than the sum of its proper divisors (31516531).

220615661 is an equidigital number, since it uses as much as digits as its factorization.

220615661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31516530.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 220615661 is about 14853.1364027939. The cubic root of 220615661 is about 604.2436747965.

The spelling of 220615661 in words is "two hundred twenty million, six hundred fifteen thousand, six hundred sixty-one".