20990217 has 4 divisors (see below), whose sum is σ = 27986960. Its totient is φ = 13993476.

The previous prime is 20990209. The next prime is 20990243. The reversal of 20990217 is 71209902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 20990217 - 2³ = 20990209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20992217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3498367 + ... + 3498372.

It is an arithmetic number, because the mean of its divisors is an integer number (6996740).

Almost surely, 2^20990217 is an apocalyptic number.

It is an amenable number.

20990217 is a deficient number, since it is larger than the sum of its proper divisors (6996743).

20990217 is an equidigital number, since it uses as much as digits as its factorization.

20990217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6996742.

The product of its (nonzero) digits is 2268, while the sum is 30.

The square root of 20990217 is about 4581.5081578013. The cubic root of 20990217 is about 275.8495688325.

The spelling of 20990217 in words is "twenty million, nine hundred ninety thousand, two hundred seventeen".