28781780 has 12 divisors (see below), whose sum is σ = 60441780. Its totient is φ = 11512704.

The previous prime is 28781773. The next prime is 28781807. The reversal of 28781780 is 8718782.

It can be written as a sum of positive squares in 2 ways, for example, as 20232004 + 8549776 = 4498^2 + 2924^2 .

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 719525 + ... + 719564.

It is an arithmetic number, because the mean of its divisors is an integer number (5036815).

Almost surely, 2^28781780 is an apocalyptic number.

28781780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28781780 is an abundant number, since it is smaller than the sum of its proper divisors (31660000).

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

28781780 is a wasteful number, since it uses less digits than its factorization.

28781780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1439098 (or 1439096 counting only the distinct ones).

The product of its (nonzero) digits is 50176, while the sum is 41.

The square root of 28781780 is about 5364.8653291579. The cubic root of 28781780 is about 306.4591197017.

The spelling of 28781780 in words is "twenty-eight million, seven hundred eighty-one thousand, seven hundred eighty".