19898221 has 4 divisors (see below), whose sum is σ = 22740832. Its totient is φ = 17055612.

The previous prime is 19898213. The next prime is 19898227. The reversal of 19898221 is 12289891.

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 19898221 - 2³ = 19898213 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 (19898227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1421295 + ... + 1421308.

It is an arithmetic number, because the mean of its divisors is an integer number (5685208).

Almost surely, 2^19898221 is an apocalyptic number.

It is an amenable number.

19898221 is a deficient number, since it is larger than the sum of its proper divisors (2842611).

19898221 is an equidigital number, since it uses as much as digits as its factorization.

19898221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2842610.

The product of its digits is 20736, while the sum is 40.

The square root of 19898221 is about 4460.7422028178. The cubic root of 19898221 is about 270.9805271884.

The spelling of 19898221 in words is "nineteen million, eight hundred ninety-eight thousand, two hundred twenty-one".