221561663 has 16 divisors (see below), whose sum is σ = 241496640. Its totient is φ = 202444800.

The previous prime is 221561651. The next prime is 221561689. The reversal of 221561663 is 366165122.

It is a cyclic number.

It is not a de Polignac number, because 221561663 - 2⁸ = 221561407 is a prime.

It is a super-2 number, since 2×221561663² = 98179141022651138, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221561623) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 167318 + ... + 168636.

It is an arithmetic number, because the mean of its divisors is an integer number (15093540).

Almost surely, 2^221561663 is an apocalyptic number.

221561663 is a deficient number, since it is larger than the sum of its proper divisors (19934977).

221561663 is a wasteful number, since it uses less digits than its factorization.

221561663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1618.

The product of its digits is 12960, while the sum is 32.

The square root of 221561663 is about 14884.9475309791. The cubic root of 221561663 is about 605.1061107509.

The spelling of 221561663 in words is "two hundred twenty-one million, five hundred sixty-one thousand, six hundred sixty-three".