139531 has 8 divisors (see below), whose sum is σ = 164864. Its totient is φ = 115560.

The previous prime is 139511. The next prime is 139537. The reversal of 139531 is 135931.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 139531 - 2¹¹ = 137483 is a prime.

It is a super-2 number, since 2×139531² = 38937799922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (139537) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 105 + ... + 538.

It is an arithmetic number, because the mean of its divisors is an integer number (20608).

2¹³⁹⁵³¹ is an apocalyptic number.

139531 is a deficient number, since it is larger than the sum of its proper divisors (25333).

139531 is an equidigital number, since it uses as much as digits as its factorization.

139531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 681.

The product of its digits is 405, while the sum is 22.

The square root of 139531 is about 373.5384852997. The cubic root of 139531 is about 51.8668932994.

Subtracting from 139531 its reverse (135931), we obtain a square (3600 = 60²).

The spelling of 139531 in words is "one hundred thirty-nine thousand, five hundred thirty-one".