138236440421 has 2 divisors, whose sum is σ = 138236440422. Its totient is φ = 138236440420.

The previous prime is 138236440411. The next prime is 138236440487. The reversal of 138236440421 is 124044632831.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 122230648225 + 16005792196 = 349615^2 + 126514^2 .

It is a cyclic number.

It is not a de Polignac number, because 138236440421 - 2²⁶ = 138169331557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138236440411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69118220210 + 69118220211.

It is an arithmetic number, because the mean of its divisors is an integer number (69118220211).

Almost surely, 2^138236440421 is an apocalyptic number.

It is an amenable number.

138236440421 is a deficient number, since it is larger than the sum of its proper divisors (1).

138236440421 is an equidigital number, since it uses as much as digits as its factorization.

138236440421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 110592, while the sum is 38.

The spelling of 138236440421 in words is "one hundred thirty-eight billion, two hundred thirty-six million, four hundred forty thousand, four hundred twenty-one".