15661223 has 2 divisors, whose sum is σ = 15661224. Its totient is φ = 15661222.

The previous prime is 15661213. The next prime is 15661273. The reversal of 15661223 is 32216651.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15661223 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 15661192 and 15661201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15661213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7830611 + 7830612.

It is an arithmetic number, because the mean of its divisors is an integer number (7830612).

Almost surely, 2^15661223 is an apocalyptic number.

15661223 is a deficient number, since it is larger than the sum of its proper divisors (1).

15661223 is an equidigital number, since it uses as much as digits as its factorization.

15661223 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2160, while the sum is 26.

The square root of 15661223 is about 3957.4263101162. The cubic root of 15661223 is about 250.1930402368.

Adding to 15661223 its reverse (32216651), we get a palindrome (47877874).

The spelling of 15661223 in words is "fifteen million, six hundred sixty-one thousand, two hundred twenty-three".