138232421 has 2 divisors, whose sum is σ = 138232422. Its totient is φ = 138232420.

The previous prime is 138232411. The next prime is 138232439. The reversal of 138232421 is 124232831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 128709025 + 9523396 = 11345^2 + 3086^2 .

It is an emirp because it is prime and its reverse (124232831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138232421 - 2¹⁰ = 138231397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138232411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69116210 + 69116211.

It is an arithmetic number, because the mean of its divisors is an integer number (69116211).

Almost surely, 2^138232421 is an apocalyptic number.

It is an amenable number.

138232421 is a deficient number, since it is larger than the sum of its proper divisors (1).

138232421 is an equidigital number, since it uses as much as digits as its factorization.

138232421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2304, while the sum is 26.

The square root of 138232421 is about 11757.2284574214. The cubic root of 138232421 is about 517.0548760944.

The spelling of 138232421 in words is "one hundred thirty-eight million, two hundred thirty-two thousand, four hundred twenty-one".