28689920 has 80 divisors (see below), whose sum is σ = 78664608. Its totient is φ = 9830400.

The previous prime is 28689889. The next prime is 28689953. The reversal of 28689920 is 2998682.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×28689920² = 1646223019212800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17120 + ... + 18720.

Almost surely, 2^28689920 is an apocalyptic number.

28689920 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 28689920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39332304).

28689920 is an abundant number, since it is smaller than the sum of its proper divisors (49974688).

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

28689920 is an equidigital number, since it uses as much as digits as its factorization.

28689920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1631 (or 1615 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 44.

The square root of 28689920 is about 5356.2972284966. The cubic root of 28689920 is about 306.1327403367.

The spelling of 28689920 in words is "twenty-eight million, six hundred eighty-nine thousand, nine hundred twenty".