138557 has 4 divisors (see below), whose sum is σ = 139776. Its totient is φ = 137340.

The previous prime is 138547. The next prime is 138559. The reversal of 138557 is 755831.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 755831 = 163 ⋅4637.

It is a cyclic number.

It is not a de Polignac number, because 138557 - 2⁶ = 138493 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 11.

It is a congruent number.

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, 419 + ... + 672.

It is an arithmetic number, because the mean of its divisors is an integer number (34944).

2¹³⁸⁵⁵⁷ is an apocalyptic number.

It is an amenable number.

138557 is a deficient number, since it is larger than the sum of its proper divisors (1219).

138557 is a wasteful number, since it uses less digits than its factorization.

138557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1218.

The product of its digits is 4200, while the sum is 29.

The square root of 138557 is about 372.2324542541. The cubic root of 138557 is about 51.7459252939.

The spelling of 138557 in words is "one hundred thirty-eight thousand, five hundred fifty-seven".