123555566779 has 4 divisors (see below), whose sum is σ = 125399679784. Its totient is φ = 121711453776.

The previous prime is 123555566767. The next prime is 123555566801. The reversal of 123555566779 is 977665555321.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 123555566779 - 2⁵ = 123555566747 is a prime.

It is a Duffinian number.

It is a plaindrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (123555566479) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 922056402 + ... + 922056535.

It is an arithmetic number, because the mean of its divisors is an integer number (31349919946).

Almost surely, 2^123555566779 is an apocalyptic number.

123555566779 is a deficient number, since it is larger than the sum of its proper divisors (1844113005).

123555566779 is an equidigital number, since it uses as much as digits as its factorization.

123555566779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1844113004.

The product of its digits is 59535000, while the sum is 61.

The spelling of 123555566779 in words is "one hundred twenty-three billion, five hundred fifty-five million, five hundred sixty-six thousand, seven hundred seventy-nine".