20661223 has 4 divisors (see below), whose sum is σ = 22539528. Its totient is φ = 18782920.

The previous prime is 20661203. The next prime is 20661233. The reversal of 20661223 is 32216602.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20661223 - 2⁵ = 20661191 is a prime.

It is a super-2 number, since 2×20661223² = 853772271711458, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20661194 and 20661203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20661203) 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, 939136 + ... + 939157.

It is an arithmetic number, because the mean of its divisors is an integer number (5634882).

Almost surely, 2^20661223 is an apocalyptic number.

20661223 is a deficient number, since it is larger than the sum of its proper divisors (1878305).

20661223 is a wasteful number, since it uses less digits than its factorization.

20661223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1878304.

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 20661223 is about 4545.4618027215. The cubic root of 20661223 is about 274.4007801078.

Adding to 20661223 its reverse (32216602), we get a palindrome (52877825).

The spelling of 20661223 in words is "twenty million, six hundred sixty-one thousand, two hundred twenty-three".