22428721 has 12 divisors (see below), whose sum is σ = 27464880. Its totient is φ = 18212040.

The previous prime is 22428709. The next prime is 22428727. The reversal of 22428721 is 12782422.

It is not a de Polignac number, because 22428721 - 2⁹ = 22428209 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 22428721.

It is not an unprimeable number, because it can be changed into a prime (22428727) 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, 11115 + ... + 12976.

It is an arithmetic number, because the mean of its divisors is an integer number (2288740).

Almost surely, 2^22428721 is an apocalyptic number.

It is an amenable number.

22428721 is a deficient number, since it is larger than the sum of its proper divisors (5036159).

22428721 is a wasteful number, since it uses less digits than its factorization.

22428721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24124 (or 24117 counting only the distinct ones).

The product of its digits is 3584, while the sum is 28.

The square root of 22428721 is about 4735.8970639151. The cubic root of 22428721 is about 282.0123772714.

The spelling of 22428721 in words is "twenty-two million, four hundred twenty-eight thousand, seven hundred twenty-one".