139521 has 4 divisors (see below), whose sum is σ = 186032. Its totient is φ = 93012.

The previous prime is 139511. The next prime is 139537. The reversal of 139521 is 125931.

139521 is an esthetic number in base 9, because in such base its adjacent digits differ by 1.

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.

It is not a de Polignac number, because 139521 - 2⁶ = 139457 is a prime.

It is a super-2 number, since 2×139521² = 38932218882, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a plaindrome in base 14.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 139521.

It is not an unprimeable number, because it can be changed into a prime (139501) 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, 23251 + ... + 23256.

It is an arithmetic number, because the mean of its divisors is an integer number (46508).

2¹³⁹⁵²¹ is an apocalyptic number.

It is an amenable number.

139521 is a deficient number, since it is larger than the sum of its proper divisors (46511).

139521 is an equidigital number, since it uses as much as digits as its factorization.

139521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46510.

The product of its digits is 270, while the sum is 21.

The square root of 139521 is about 373.5250995582. The cubic root of 139521 is about 51.8656541929.

The spelling of 139521 in words is "one hundred thirty-nine thousand, five hundred twenty-one".