20001505 has 4 divisors (see below), whose sum is σ = 24001812. Its totient is φ = 16001200.

The previous prime is 20001491. The next prime is 20001517. The reversal of 20001505 is 50510002.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50510002 = 2 ⋅25255001.

It can be written as a sum of positive squares in 2 ways, for example, as 7667361 + 12334144 = 2769^2 + 3512^2 .

It is not a de Polignac number, because 20001505 - 2¹⁵ = 19968737 is a prime.

It is a Smith number, since the sum of its digits (13) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2000146 + ... + 2000155.

It is an arithmetic number, because the mean of its divisors is an integer number (6000453).

Almost surely, 2^20001505 is an apocalyptic number.

It is an amenable number.

20001505 is a deficient number, since it is larger than the sum of its proper divisors (4000307).

20001505 is an equidigital number, since it uses as much as digits as its factorization.

20001505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4000306.

The product of its (nonzero) digits is 50, while the sum is 13.

The square root of 20001505 is about 4472.3042159495. The cubic root of 20001505 is about 271.4485701529.

Adding to 20001505 its reverse (50510002), we get a palindrome (70511507).

The spelling of 20001505 in words is "twenty million, one thousand, five hundred five".