221561823 has 8 divisors (see below), whose sum is σ = 337618048. Its totient is φ = 126606744.

The previous prime is 221561779. The next prime is 221561839. The reversal of 221561823 is 328165122.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 221561823 - 2⁸ = 221561567 is a prime.

It is a super-2 number, since 2×221561823² = 98179282822166658, 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 (221561423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5275261 + ... + 5275302.

It is an arithmetic number, because the mean of its divisors is an integer number (42202256).

Almost surely, 2^221561823 is an apocalyptic number.

221561823 is a deficient number, since it is larger than the sum of its proper divisors (116056225).

221561823 is a wasteful number, since it uses less digits than its factorization.

221561823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10550573.

The product of its digits is 5760, while the sum is 30.

The square root of 221561823 is about 14884.9529055352. The cubic root of 221561823 is about 605.1062564093.

The spelling of 221561823 in words is "two hundred twenty-one million, five hundred sixty-one thousand, eight hundred twenty-three".