139439521 has 8 divisors (see below), whose sum is σ = 150603264. Its totient is φ = 128338320.

The previous prime is 139439513. The next prime is 139439539. The reversal of 139439521 is 125934931.

139439521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 139439521 - 2³ = 139439513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (139439021) 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, 10945 + ... + 19966.

It is an arithmetic number, because the mean of its divisors is an integer number (18825408).

Almost surely, 2^139439521 is an apocalyptic number.

It is an amenable number.

139439521 is a deficient number, since it is larger than the sum of its proper divisors (11163743).

139439521 is a wasteful number, since it uses less digits than its factorization.

139439521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31271.

The product of its digits is 29160, while the sum is 37.

The square root of 139439521 is about 11808.4512532338. The cubic root of 139439521 is about 518.5555586946. Note that the first 5 decimals are identical.

The spelling of 139439521 in words is "one hundred thirty-nine million, four hundred thirty-nine thousand, five hundred twenty-one".