123561931 has 2 divisors, whose sum is σ = 123561932. Its totient is φ = 123561930.

The previous prime is 123561929. The next prime is 123561937. The reversal of 123561931 is 139165321.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 123561931 - 2¹ = 123561929 is a prime.

It is a super-2 number, since 2×123561931² = 30535101584897522, which contains 22 as substring.

Together with 123561929, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 123561893 and 123561902.

It is not a weakly prime, because it can be changed into another prime (123561937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61780965 + 61780966.

It is an arithmetic number, because the mean of its divisors is an integer number (61780966).

Almost surely, 2^123561931 is an apocalyptic number.

123561931 is a deficient number, since it is larger than the sum of its proper divisors (1).

123561931 is an equidigital number, since it uses as much as digits as its factorization.

123561931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4860, while the sum is 31.

The square root of 123561931 is about 11115.8414436335. The cubic root of 123561931 is about 498.0751742670.

The spelling of 123561931 in words is "one hundred twenty-three million, five hundred sixty-one thousand, nine hundred thirty-one".