28261840 has 40 divisors (see below), whose sum is σ = 65931048. Its totient is φ = 11266560.

The previous prime is 28261819. The next prime is 28261843. The reversal of 28261840 is 4816282.

It can be written as a sum of positive squares in 4 ways, for example, as 467856 + 27793984 = 684^2 + 5272^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28261843) 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, 42954 + ... + 43606.

Almost surely, 2^28261840 is an apocalyptic number.

28261840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28261840 is an abundant number, since it is smaller than the sum of its proper divisors (37669208).

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

28261840 is a wasteful number, since it uses less digits than its factorization.

28261840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1207 (or 1201 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 31.

The square root of 28261840 is about 5316.1866031959. The cubic root of 28261840 is about 304.6025100579.

The spelling of 28261840 in words is "twenty-eight million, two hundred sixty-one thousand, eight hundred forty".