156623221 has 2 divisors, whose sum is σ = 156623222. Its totient is φ = 156623220.

The previous prime is 156623219. The next prime is 156623263. The reversal of 156623221 is 122326651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 151560721 + 5062500 = 12311^2 + 2250^2 .

It is a cyclic number.

It is not a de Polignac number, because 156623221 - 2¹ = 156623219 is a prime.

Together with 156623219, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 156623221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (156623521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 78311610 + 78311611.

It is an arithmetic number, because the mean of its divisors is an integer number (78311611).

Almost surely, 2^156623221 is an apocalyptic number.

It is an amenable number.

156623221 is a deficient number, since it is larger than the sum of its proper divisors (1).

156623221 is an equidigital number, since it uses as much as digits as its factorization.

156623221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 28.

The square root of 156623221 is about 12514.9199358206. The cubic root of 156623221 is about 539.0371743240.

Adding to 156623221 its reverse (122326651), we get a palindrome (278949872).

The spelling of 156623221 in words is "one hundred fifty-six million, six hundred twenty-three thousand, two hundred twenty-one".