138551 has 4 divisors (see below), whose sum is σ = 158352. Its totient is φ = 118752.

The previous prime is 138547. The next prime is 138559. The reversal of 138551 is 155831.

138551 = 71² + 72² + ... + 91².

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 155831 = 13 ⋅11987.

It is a cyclic number.

It is not a de Polignac number, because 138551 - 2² = 138547 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 138551.

It is not an unprimeable number, because it can be changed into a prime (138559) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9890 + ... + 9903.

It is an arithmetic number, because the mean of its divisors is an integer number (39588).

2¹³⁸⁵⁵¹ is an apocalyptic number.

138551 is a deficient number, since it is larger than the sum of its proper divisors (19801).

138551 is an equidigital number, since it uses as much as digits as its factorization.

138551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19800.

The product of its digits is 600, while the sum is 23.

The square root of 138551 is about 372.2243946869. The cubic root of 138551 is about 51.7451783570.

The spelling of 138551 in words is "one hundred thirty-eight thousand, five hundred fifty-one".