28019321 has 4 divisors (see below), whose sum is σ = 30566544. Its totient is φ = 25472100.

The previous prime is 28019317. The next prime is 28019347. The reversal of 28019321 is 12391082.

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 28019321 - 2² = 28019317 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28019311) 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, 1273595 + ... + 1273616.

It is an arithmetic number, because the mean of its divisors is an integer number (7641636).

Almost surely, 2^28019321 is an apocalyptic number.

It is an amenable number.

28019321 is a deficient number, since it is larger than the sum of its proper divisors (2547223).

28019321 is a wasteful number, since it uses less digits than its factorization.

28019321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2547222.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 28019321 is about 5293.3279701904. The cubic root of 28019321 is about 303.7287262898.

The spelling of 28019321 in words is "twenty-eight million, nineteen thousand, three hundred twenty-one".