28307240 has 32 divisors (see below), whose sum is σ = 68591880. Its totient is φ = 10451712.

The previous prime is 28307231. The next prime is 28307243. The reversal of 28307240 is 4270382.

It can be written as a sum of positive squares in 4 ways, for example, as 11546404 + 16760836 = 3398^2 + 4094^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28307243) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26699 + ... + 27738.

Almost surely, 2^28307240 is an apocalyptic number.

28307240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28307240 is an abundant number, since it is smaller than the sum of its proper divisors (40284640).

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

28307240 is a wasteful number, since it uses less digits than its factorization.

28307240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54461 (or 54457 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 26.

The square root of 28307240 is about 5320.4548677721. The cubic root of 28307240 is about 304.7655279362.

The spelling of 28307240 in words is "twenty-eight million, three hundred seven thousand, two hundred forty".