138428621 has 2 divisors, whose sum is σ = 138428622. Its totient is φ = 138428620.

The previous prime is 138428557. The next prime is 138428683. The reversal of 138428621 is 126824831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 117397225 + 21031396 = 10835^2 + 4586^2 .

It is a cyclic number.

It is not a de Polignac number, because 138428621 - 2⁶ = 138428557 is a prime.

It is a super-2 number, since 2×138428621² = 38324966223923282, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138428321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69214310 + 69214311.

It is an arithmetic number, because the mean of its divisors is an integer number (69214311).

Almost surely, 2^138428621 is an apocalyptic number.

It is an amenable number.

138428621 is a deficient number, since it is larger than the sum of its proper divisors (1).

138428621 is an equidigital number, since it uses as much as digits as its factorization.

138428621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18432, while the sum is 35.

The square root of 138428621 is about 11765.5693019930. The cubic root of 138428621 is about 517.2993874952.

The spelling of 138428621 in words is "one hundred thirty-eight million, four hundred twenty-eight thousand, six hundred twenty-one".