123137821 has 2 divisors, whose sum is σ = 123137822. Its totient is φ = 123137820.

The previous prime is 123137809. The next prime is 123137849. The reversal of 123137821 is 128731321.

It is an a-pointer prime, because the next prime (123137849) can be obtained adding 123137821 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 122345721 + 792100 = 11061^2 + 890^2 .

It is a cyclic number.

It is not a de Polignac number, because 123137821 - 2¹⁷ = 123006749 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 123137821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (123137621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 61568910 + 61568911.

It is an arithmetic number, because the mean of its divisors is an integer number (61568911).

Almost surely, 2^123137821 is an apocalyptic number.

It is an amenable number.

123137821 is a deficient number, since it is larger than the sum of its proper divisors (1).

123137821 is an equidigital number, since it uses as much as digits as its factorization.

123137821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2016, while the sum is 28.

The square root of 123137821 is about 11096.7482173833. The cubic root of 123137821 is about 497.5046619598.

The spelling of 123137821 in words is "one hundred twenty-three million, one hundred thirty-seven thousand, eight hundred twenty-one".