123612561 has 20 divisors (see below), whose sum is σ = 186001200. Its totient is φ = 81808056.

The previous prime is 123612551. The next prime is 123612571. The reversal of 123612561 is 165216321.

It is an interprime number because it is at equal distance from previous prime (123612551) and next prime (123612571).

It is a de Polignac number, because none of the positive numbers 2^k-123612561 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an alternating number because its digits alternate between odd and even.

It is not an unprimeable number, because it can be changed into a prime (123612551) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 5770 + ... + 16748.

It is an arithmetic number, because the mean of its divisors is an integer number (9300060).

Almost surely, 2^123612561 is an apocalyptic number.

It is an amenable number.

123612561 is a deficient number, since it is larger than the sum of its proper divisors (62388639).

123612561 is a wasteful number, since it uses less digits than its factorization.

123612561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11130 (or 11121 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 123612561 is about 11118.1185908408. The cubic root of 123612561 is about 498.1431944151.

Adding to 123612561 its reverse (165216321), we get a palindrome (288828882).

The spelling of 123612561 in words is "one hundred twenty-three million, six hundred twelve thousand, five hundred sixty-one".