28709820 has 36 divisors (see below), whose sum is σ = 87087000. Its totient is φ = 7655904.

The previous prime is 28709801. The next prime is 28709851. The reversal of 28709820 is 2890782.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 79570 + ... + 79929.

Almost surely, 2^28709820 is an apocalyptic number.

28709820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28709820 is an abundant number, since it is smaller than the sum of its proper divisors (58377180).

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

28709820 is a wasteful number, since it uses less digits than its factorization.

28709820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159514 (or 159509 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

The square root of 28709820 is about 5358.1545330459. The cubic root of 28709820 is about 306.2035042560.

The spelling of 28709820 in words is "twenty-eight million, seven hundred nine thousand, eight hundred twenty".