20992005 has 18 divisors (see below), whose sum is σ = 36439494. Its totient is φ = 11179344.

The previous prime is 20991989. The next prime is 20992007. The reversal of 20992005 is 50029902.

It can be written as a sum of positive squares in only one way, i.e., 16793604 + 4198401 = 4098^2 + 2049^2 .

It is not a de Polignac number, because 20992005 - 2⁴ = 20991989 is a prime.

It is a zygodrome in base 4.

It is a self number, because there is not a number n which added to its sum of digits gives 20992005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20992007) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 30394 + ... + 31076.

Almost surely, 2^20992005 is an apocalyptic number.

It is an amenable number.

20992005 is a deficient number, since it is larger than the sum of its proper divisors (15447489).

20992005 is an frugal number, since it uses more digits than its factorization.

20992005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1377 (or 691 counting only the distinct ones).

The product of its (nonzero) digits is 1620, while the sum is 27.

The square root of 20992005 is about 4581.7032858971. The cubic root of 20992005 is about 275.8574011324.

Multiplying 20992005 by its product of nonzero digits (1620), we get a square (34007048100 = 184410²).

The spelling of 20992005 in words is "twenty million, nine hundred ninety-two thousand, five".