123138583661 has 2 divisors, whose sum is σ = 123138583662. Its totient is φ = 123138583660.

The previous prime is 123138583651. The next prime is 123138583721. The reversal of 123138583661 is 166385831321.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 85383762025 + 37754821636 = 292205^2 + 194306^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-123138583661 is a prime.

It is a super-2 number, since 2×123138583661² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (123138583651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61569291830 + 61569291831.

It is an arithmetic number, because the mean of its divisors is an integer number (61569291831).

Almost surely, 2^123138583661 is an apocalyptic number.

It is an amenable number.

123138583661 is a deficient number, since it is larger than the sum of its proper divisors (1).

123138583661 is an equidigital number, since it uses as much as digits as its factorization.

123138583661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 622080, while the sum is 47.

The spelling of 123138583661 in words is "one hundred twenty-three billion, one hundred thirty-eight million, five hundred eighty-three thousand, six hundred sixty-one".