20990221 has 8 divisors (see below), whose sum is σ = 24293120. Its totient is φ = 17763408.

The previous prime is 20990209. The next prime is 20990243. The reversal of 20990221 is 12209902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20990221 - 2¹¹ = 20988173 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20990521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18426 + ... + 19531.

It is an arithmetic number, because the mean of its divisors is an integer number (3036640).

Almost surely, 2^20990221 is an apocalyptic number.

It is an amenable number.

20990221 is a deficient number, since it is larger than the sum of its proper divisors (3302899).

20990221 is an equidigital number, since it uses as much as digits as its factorization.

20990221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38043.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 20990221 is about 4581.5085943388. The cubic root of 20990221 is about 275.8495863549.

The spelling of 20990221 in words is "twenty million, nine hundred ninety thousand, two hundred twenty-one".