19321921 has 4 divisors (see below), whose sum is σ = 19771312. Its totient is φ = 18872532.

The previous prime is 19321919. The next prime is 19321927. The reversal of 19321921 is 12912391.

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 19321921 - 2¹ = 19321919 is a prime.

It is a super-2 number, since 2×19321921² = 746673262260482, which contains 22 as substring.

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 19321921.

It is not an unprimeable number, because it can be changed into a prime (19321927) 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, 224631 + ... + 224716.

It is an arithmetic number, because the mean of its divisors is an integer number (4942828).

Almost surely, 2^19321921 is an apocalyptic number.

It is an amenable number.

19321921 is a deficient number, since it is larger than the sum of its proper divisors (449391).

19321921 is an equidigital number, since it uses as much as digits as its factorization.

19321921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 449390.

The product of its digits is 972, while the sum is 28.

The square root of 19321921 is about 4395.6707110520. The cubic root of 19321921 is about 268.3387757427.

The spelling of 19321921 in words is "nineteen million, three hundred twenty-one thousand, nine hundred twenty-one".