138617621 has 2 divisors, whose sum is σ = 138617622. Its totient is φ = 138617620.

The previous prime is 138617603. The next prime is 138617639. The reversal of 138617621 is 126716831.

It is a balanced prime because it is at equal distance from previous prime (138617603) and next prime (138617639).

It can be written as a sum of positive squares in only one way, i.e., 116424100 + 22193521 = 10790^2 + 4711^2 .

It is a cyclic number.

It is not a de Polignac number, because 138617621 - 2²⁶ = 71508757 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138617641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69308810 + 69308811.

It is an arithmetic number, because the mean of its divisors is an integer number (69308811).

Almost surely, 2^138617621 is an apocalyptic number.

It is an amenable number.

138617621 is a deficient number, since it is larger than the sum of its proper divisors (1).

138617621 is an equidigital number, since it uses as much as digits as its factorization.

138617621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 35.

The square root of 138617621 is about 11773.5984728544. The cubic root of 138617621 is about 517.5347076226.

The spelling of 138617621 in words is "one hundred thirty-eight million, six hundred seventeen thousand, six hundred twenty-one".