28073921 has 4 divisors (see below), whose sum is σ = 28236372. Its totient is φ = 27911472.

The previous prime is 28073917. The next prime is 28073923. The reversal of 28073921 is 12937082.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12937082 = 2 ⋅6468541.

It can be written as a sum of positive squares in 2 ways, for example, as 13359025 + 14714896 = 3655^2 + 3836^2 .

It is a cyclic number.

It is not a de Polignac number, because 28073921 - 2² = 28073917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28073923) 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, 80966 + ... + 81311.

It is an arithmetic number, because the mean of its divisors is an integer number (7059093).

Almost surely, 2^28073921 is an apocalyptic number.

It is an amenable number.

28073921 is a deficient number, since it is larger than the sum of its proper divisors (162451).

28073921 is a wasteful number, since it uses less digits than its factorization.

28073921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162450.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 28073921 is about 5298.4828960751. The cubic root of 28073921 is about 303.9258858166.

The spelling of 28073921 in words is "twenty-eight million, seventy-three thousand, nine hundred twenty-one".