28947780 has 120 divisors (see below), whose sum is σ = 92207808. Its totient is φ = 7601472.

The previous prime is 28947739. The next prime is 28947791. The reversal of 28947780 is 8774982.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 173257 + ... + 173423.

Almost surely, 2^28947780 is an apocalyptic number.

28947780 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 28947780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46103904).

28947780 is an abundant number, since it is smaller than the sum of its proper divisors (63260028).

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

28947780 is a wasteful number, since it uses less digits than its factorization.

28947780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295 (or 284 counting only the distinct ones).

The product of its (nonzero) digits is 225792, while the sum is 45.

The square root of 28947780 is about 5380.3141172240. The cubic root of 28947780 is about 307.0471621320.

The spelling of 28947780 in words is "twenty-eight million, nine hundred forty-seven thousand, seven hundred eighty".