636561623 has 2 divisors, whose sum is σ = 636561624. Its totient is φ = 636561622.

The previous prime is 636561599. The next prime is 636561661. The reversal of 636561623 is 326165636.

It is a happy number.

It is an a-pointer prime, because the next prime (636561661) can be obtained adding 636561623 to its sum of digits (38).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 636561623 - 2¹⁶ = 636496087 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (636560623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 318280811 + 318280812.

It is an arithmetic number, because the mean of its divisors is an integer number (318280812).

Almost surely, 2^636561623 is an apocalyptic number.

636561623 is a deficient number, since it is larger than the sum of its proper divisors (1).

636561623 is an equidigital number, since it uses as much as digits as its factorization.

636561623 is an evil number, because the sum of its binary digits is even.

The product of its digits is 116640, while the sum is 38.

The square root of 636561623 is about 25230.1728690075. The cubic root of 636561623 is about 860.2278209303.

The spelling of 636561623 in words is "six hundred thirty-six million, five hundred sixty-one thousand, six hundred twenty-three".