123656220431 has 4 divisors (see below), whose sum is σ = 123668424264. Its totient is φ = 123644016600.

The previous prime is 123656220421. The next prime is 123656220439. The reversal of 123656220431 is 134022656321.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-123656220431 is a prime.

It is a super-2 number, since 2×123656220431² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 123656220391 and 123656220400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (123656220439) 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, 6086705 + ... + 6106986.

It is an arithmetic number, because the mean of its divisors is an integer number (30917106066).

Almost surely, 2^123656220431 is an apocalyptic number.

123656220431 is a deficient number, since it is larger than the sum of its proper divisors (12203833).

123656220431 is a wasteful number, since it uses less digits than its factorization.

123656220431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12203832.

The product of its (nonzero) digits is 51840, while the sum is 35.

Adding to 123656220431 its reverse (134022656321), we get a palindrome (257678876752).

The spelling of 123656220431 in words is "one hundred twenty-three billion, six hundred fifty-six million, two hundred twenty thousand, four hundred thirty-one".