28569840 has 80 divisors (see below), whose sum is σ = 95389728. Its totient is φ = 7031808.

The previous prime is 28569839. The next prime is 28569847. The reversal of 28569840 is 4896582.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 28569792 and 28569801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28569847) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1459 + ... + 7698.

Almost surely, 2^28569840 is an apocalyptic number.

28569840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28569840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47694864).

28569840 is an abundant number, since it is smaller than the sum of its proper divisors (66819888).

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

28569840 is a wasteful number, since it uses less digits than its factorization.

28569840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9186 (or 9180 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 42.

The square root of 28569840 is about 5345.0762389324. The cubic root of 28569840 is about 305.7050427894.

It can be divided in two parts, 285 and 69840, that added together give a triangular number (70125 = T₃₇₄).

The spelling of 28569840 in words is "twenty-eight million, five hundred sixty-nine thousand, eight hundred forty".