28421640 has 96 divisors (see below), whose sum is σ = 99492120. Its totient is φ = 6994944.

The previous prime is 28421639. The next prime is 28421681. The reversal of 28421640 is 4612482.

It can be written as a sum of positive squares in 4 ways, for example, as 23677956 + 4743684 = 4866^2 + 2178^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1644 + ... + 7716.

Almost surely, 2^28421640 is an apocalyptic number.

28421640 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 28421640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49746060).

28421640 is an abundant number, since it is smaller than the sum of its proper divisors (71070480).

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

28421640 is a wasteful number, since it uses less digits than its factorization.

28421640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6103 (or 6096 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The square root of 28421640 is about 5331.1949879928. The cubic root of 28421640 is about 305.1755327487.

The spelling of 28421640 in words is "twenty-eight million, four hundred twenty-one thousand, six hundred forty".