123978109 has 2 divisors, whose sum is σ = 123978110. Its totient is φ = 123978108.

The previous prime is 123978091. The next prime is 123978121. The reversal of 123978109 is 901879321.

Together with previous prime (123978091) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 91145209 + 32832900 = 9547^2 + 5730^2 .

It is a cyclic number.

It is not a de Polignac number, because 123978109 - 2¹³ = 123969917 is a prime.

It is a super-2 number, since 2×123978109² = 30741143022431762, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (123978149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61989054 + 61989055.

It is an arithmetic number, because the mean of its divisors is an integer number (61989055).

Almost surely, 2^123978109 is an apocalyptic number.

It is an amenable number.

123978109 is a deficient number, since it is larger than the sum of its proper divisors (1).

123978109 is an equidigital number, since it uses as much as digits as its factorization.

123978109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27216, while the sum is 40.

The square root of 123978109 is about 11134.5457473576. The cubic root of 123978109 is about 498.6337487823.

The spelling of 123978109 in words is "one hundred twenty-three million, nine hundred seventy-eight thousand, one hundred nine".