123640559 has 4 divisors (see below), whose sum is σ = 141303504. Its totient is φ = 105977616.

The previous prime is 123640547. The next prime is 123640591. The reversal of 123640559 is 955046321.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 955046321 = 24179 ⋅39499.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-123640559 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (123640519) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8831462 + ... + 8831475.

It is an arithmetic number, because the mean of its divisors is an integer number (35325876).

Almost surely, 2^123640559 is an apocalyptic number.

123640559 is a deficient number, since it is larger than the sum of its proper divisors (17662945).

123640559 is an equidigital number, since it uses as much as digits as its factorization.

123640559 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17662944.

The product of its (nonzero) digits is 32400, while the sum is 35.

The square root of 123640559 is about 11119.3776354614. The cubic root of 123640559 is about 498.1808010579.

The spelling of 123640559 in words is "one hundred twenty-three million, six hundred forty thousand, five hundred fifty-nine".