123381806557 has 2 divisors, whose sum is σ = 123381806558. Its totient is φ = 123381806556.

The previous prime is 123381806543. The next prime is 123381806573. The reversal of 123381806557 is 755608183321.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 109715962756 + 13665843801 = 331234^2 + 116901^2 .

It is a cyclic number.

It is not a de Polignac number, because 123381806557 - 2²⁷ = 123247588829 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 123381806557.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (123381806357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61690903278 + 61690903279.

It is an arithmetic number, because the mean of its divisors is an integer number (61690903279).

Almost surely, 2^123381806557 is an apocalyptic number.

It is an amenable number.

123381806557 is a deficient number, since it is larger than the sum of its proper divisors (1).

123381806557 is an equidigital number, since it uses as much as digits as its factorization.

123381806557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1209600, while the sum is 49.

Adding to 123381806557 its reverse (755608183321), we get a palindrome (878989989878).

The spelling of 123381806557 in words is "one hundred twenty-three billion, three hundred eighty-one million, eight hundred six thousand, five hundred fifty-seven".