20906505 has 24 divisors (see below), whose sum is σ = 37582272. Its totient is φ = 11149488.

The previous prime is 20906503. The next prime is 20906521. The reversal of 20906505 is 50560902.

20906505 is a `hidden beast` number, since 2 + 0 + 9 + 0 + 650 + 5 = 666.

It is not a de Polignac number, because 20906505 - 2¹ = 20906503 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (20906503) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7389 + ... + 9818.

It is an arithmetic number, because the mean of its divisors is an integer number (1565928).

Almost surely, 2^20906505 is an apocalyptic number.

It is an amenable number.

20906505 is a deficient number, since it is larger than the sum of its proper divisors (16675767).

20906505 is an equidigital number, since it uses as much as digits as its factorization.

20906505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17227 (or 17215 counting only the distinct ones).

The product of its (nonzero) digits is 2700, while the sum is 27.

The square root of 20906505 is about 4572.3631745521. The cubic root of 20906505 is about 275.4823710205.

The spelling of 20906505 in words is "twenty million, nine hundred six thousand, five hundred five".