20139505 has 8 divisors (see below), whose sum is σ = 24508224. Its totient is φ = 15884400.

The previous prime is 20139503. The next prime is 20139517. The reversal of 20139505 is 50593102.

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

It is not a de Polignac number, because 20139505 - 2¹ = 20139503 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20139505.

It is not an unprimeable number, because it can be changed into a prime (20139503) 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, 28011 + ... + 28720.

It is an arithmetic number, because the mean of its divisors is an integer number (3063528).

Almost surely, 2^20139505 is an apocalyptic number.

It is an amenable number.

20139505 is a deficient number, since it is larger than the sum of its proper divisors (4368719).

20139505 is an equidigital number, since it uses as much as digits as its factorization.

20139505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56807.

The product of its (nonzero) digits is 1350, while the sum is 25.

The square root of 20139505 is about 4487.7059841304. The cubic root of 20139505 is about 272.0714246181.

The spelling of 20139505 in words is "twenty million, one hundred thirty-nine thousand, five hundred five".