28331640 has 128 divisors (see below), whose sum is σ = 97128000. Its totient is φ = 7340544.

The previous prime is 28331621. The next prime is 28331669. The reversal of 28331640 is 4613382.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 39606 + ... + 40314.

Almost surely, 2^28331640 is an apocalyptic number.

28331640 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 28331640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48564000).

28331640 is an abundant number, since it is smaller than the sum of its proper divisors (68796360).

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

28331640 is a wasteful number, since it uses less digits than its factorization.

28331640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 766 (or 756 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 28331640 is about 5322.7474108772. The cubic root of 28331640 is about 304.8530690657.

The spelling of 28331640 in words is "twenty-eight million, three hundred thirty-one thousand, six hundred forty".