661623329 has 2 divisors, whose sum is σ = 661623330. Its totient is φ = 661623328.

The previous prime is 661623283. The next prime is 661623337. The reversal of 661623329 is 923326166.

661623329 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 406103104 + 255520225 = 20152^2 + 15985^2 .

It is a cyclic number.

It is not a de Polignac number, because 661623329 - 2²⁴ = 644846113 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 661623292 and 661623301.

It is not a weakly prime, because it can be changed into another prime (661623379) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330811664 + 330811665.

It is an arithmetic number, because the mean of its divisors is an integer number (330811665).

Almost surely, 2^661623329 is an apocalyptic number.

It is an amenable number.

661623329 is a deficient number, since it is larger than the sum of its proper divisors (1).

661623329 is an equidigital number, since it uses as much as digits as its factorization.

661623329 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69984, while the sum is 38.

The square root of 661623329 is about 25722.0397519326. The cubic root of 661623329 is about 871.3720057050.

The spelling of 661623329 in words is "six hundred sixty-one million, six hundred twenty-three thousand, three hundred twenty-nine".