123561999 has 12 divisors (see below), whose sum is σ = 194703912. Its totient is φ = 74886000.

The previous prime is 123561979. The next prime is 123562009. The reversal of 123561999 is 999165321.

It is a happy number.

123561999 is a `hidden beast` number, since 1 + 23 + 5 + 619 + 9 + 9 = 666.

It is not a de Polignac number, because 123561999 - 2⁸ = 123561743 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (123561929) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 623952 + ... + 624149.

It is an arithmetic number, because the mean of its divisors is an integer number (16225326).

Almost surely, 2^123561999 is an apocalyptic number.

123561999 is a deficient number, since it is larger than the sum of its proper divisors (71141913).

123561999 is a wasteful number, since it uses less digits than its factorization.

123561999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1248118 (or 1248115 counting only the distinct ones).

The product of its digits is 131220, while the sum is 45.

The square root of 123561999 is about 11115.8445023309. The cubic root of 123561999 is about 498.0752656358.

The spelling of 123561999 in words is "one hundred twenty-three million, five hundred sixty-one thousand, nine hundred ninety-nine".