19805221 has 8 divisors (see below), whose sum is σ = 21237120. Its totient is φ = 18403008.

The previous prime is 19805207. The next prime is 19805251. The reversal of 19805221 is 12250891.

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 19805221 - 2¹⁵ = 19772453 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 19805221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19805251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6031 + ... + 8716.

It is an arithmetic number, because the mean of its divisors is an integer number (2654640).

Almost surely, 2^19805221 is an apocalyptic number.

It is an amenable number.

19805221 is a deficient number, since it is larger than the sum of its proper divisors (1431899).

19805221 is a wasteful number, since it uses less digits than its factorization.

19805221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14843.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 19805221 is about 4450.3057198354. The cubic root of 19805221 is about 270.5576995574.

The spelling of 19805221 in words is "nineteen million, eight hundred five thousand, two hundred twenty-one".