20990065 has 4 divisors (see below), whose sum is σ = 25188084. Its totient is φ = 16792048.

The previous prime is 20990033. The next prime is 20990071. The reversal of 20990065 is 56009902.

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 5363856 + 15626209 = 2316^2 + 3953^2 .

It is a cyclic number.

It is not a de Polignac number, because 20990065 - 2⁵ = 20990033 is a prime.

It is a Smith number, since the sum of its digits (31) 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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2099002 + ... + 2099011.

It is an arithmetic number, because the mean of its divisors is an integer number (6297021).

Almost surely, 2^20990065 is an apocalyptic number.

It is an amenable number.

20990065 is a deficient number, since it is larger than the sum of its proper divisors (4198019).

20990065 is an equidigital number, since it uses as much as digits as its factorization.

20990065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4198018.

The product of its (nonzero) digits is 4860, while the sum is 31.

The square root of 20990065 is about 4581.4915693473. The cubic root of 20990065 is about 275.8489029789.

Adding to 20990065 its reverse (56009902), we get a palindrome (76999967).

The spelling of 20990065 in words is "twenty million, nine hundred ninety thousand, sixty-five".