28121973 has 12 divisors (see below), whose sum is σ = 41215104. Its totient is φ = 17043400.

The previous prime is 28121969. The next prime is 28121983. The reversal of 28121973 is 37912182.

It is not a de Polignac number, because 28121973 - 2² = 28121969 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28121963) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 38373 + ... + 39098.

It is an arithmetic number, because the mean of its divisors is an integer number (3434592).

Almost surely, 2^28121973 is an apocalyptic number.

It is an amenable number.

28121973 is a deficient number, since it is larger than the sum of its proper divisors (13093131).

28121973 is a wasteful number, since it uses less digits than its factorization.

28121973 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77496 (or 77485 counting only the distinct ones).

The product of its digits is 6048, while the sum is 33.

The square root of 28121973 is about 5303.0154629230. The cubic root of 28121973 is about 304.0991892685.

The spelling of 28121973 in words is "twenty-eight million, one hundred twenty-one thousand, nine hundred seventy-three".