19719221 has 4 divisors (see below), whose sum is σ = 19807872. Its totient is φ = 19630572.

The previous prime is 19719209. The next prime is 19719229. The reversal of 19719221 is 12291791.

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 a cyclic number.

It is not a de Polignac number, because 19719221 - 2¹⁸ = 19457077 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 (19719229) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43991 + ... + 44436.

It is an arithmetic number, because the mean of its divisors is an integer number (4951968).

Almost surely, 2^19719221 is an apocalyptic number.

It is an amenable number.

19719221 is a deficient number, since it is larger than the sum of its proper divisors (88651).

19719221 is an equidigital number, since it uses as much as digits as its factorization.

19719221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88650.

The product of its digits is 2268, while the sum is 32.

The square root of 19719221 is about 4440.6329503799. The cubic root of 19719221 is about 270.1655180819.

The spelling of 19719221 in words is "nineteen million, seven hundred nineteen thousand, two hundred twenty-one".