28723428 has 36 divisors (see below), whose sum is σ = 72809100. Its totient is φ = 9547776.

The previous prime is 28723423. The next prime is 28723447. The reversal of 28723428 is 82432782.

It can be written as a sum of positive squares in 2 ways, for example, as 16064064 + 12659364 = 4008^2 + 3558^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 28723392 and 28723401.

It is not an unprimeable number, because it can be changed into a prime (28723423) 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, 15276 + ... + 17052.

It is an arithmetic number, because the mean of its divisors is an integer number (2022475).

Almost surely, 2^28723428 is an apocalyptic number.

It is an amenable number.

28723428 is an abundant number, since it is smaller than the sum of its proper divisors (44085672).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28723428 is a wasteful number, since it uses less digits than its factorization.

28723428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2236 (or 2231 counting only the distinct ones).

The product of its digits is 43008, while the sum is 36.

The square root of 28723428 is about 5359.4242228060. The cubic root of 28723428 is about 306.2518751516.

The spelling of 28723428 in words is "twenty-eight million, seven hundred twenty-three thousand, four hundred twenty-eight".