28770640 has 20 divisors (see below), whose sum is σ = 66891924. Its totient is φ = 11508224.

The previous prime is 28770611. The next prime is 28770649. The reversal of 28770640 is 4607782.

It can be written as a sum of positive squares in 2 ways, for example, as 12222016 + 16548624 = 3496^2 + 4068^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 28770596 and 28770605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28770649) 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, 179737 + ... + 179896.

Almost surely, 2^28770640 is an apocalyptic number.

28770640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28770640 is an abundant number, since it is smaller than the sum of its proper divisors (38121284).

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

28770640 is a wasteful number, since it uses less digits than its factorization.

28770640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 359646 (or 359640 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 34.

The square root of 28770640 is about 5363.8269919900. The cubic root of 28770640 is about 306.4195762227.

The spelling of 28770640 in words is "twenty-eight million, seven hundred seventy thousand, six hundred forty".