20155505 has 4 divisors (see below), whose sum is σ = 24186612. Its totient is φ = 16124400.

The previous prime is 20155501. The next prime is 20155511. The reversal of 20155505 is 50555102.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14167696 + 5987809 = 3764^2 + 2447^2 .

It is not a de Polignac number, because 20155505 - 2² = 20155501 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20155501) 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, 2015546 + ... + 2015555.

It is an arithmetic number, because the mean of its divisors is an integer number (6046653).

Almost surely, 2^20155505 is an apocalyptic number.

It is an amenable number.

20155505 is a deficient number, since it is larger than the sum of its proper divisors (4031107).

20155505 is an equidigital number, since it uses as much as digits as its factorization.

20155505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4031106.

The product of its (nonzero) digits is 1250, while the sum is 23.

The square root of 20155505 is about 4489.4882781894. The cubic root of 20155505 is about 272.1434553607.

The spelling of 20155505 in words is "twenty million, one hundred fifty-five thousand, five hundred five".