28781871 has 4 divisors (see below), whose sum is σ = 38375832. Its totient is φ = 19187912.

The previous prime is 28781849. The next prime is 28781873. The reversal of 28781871 is 17818782.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28781871 - 2⁵ = 28781839 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28781873) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4796976 + ... + 4796981.

It is an arithmetic number, because the mean of its divisors is an integer number (9593958).

Almost surely, 2^28781871 is an apocalyptic number.

28781871 is a deficient number, since it is larger than the sum of its proper divisors (9593961).

28781871 is an equidigital number, since it uses as much as digits as its factorization.

28781871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9593960.

The product of its digits is 50176, while the sum is 42.

The square root of 28781871 is about 5364.8738102587. The cubic root of 28781871 is about 306.4594426810.

The spelling of 28781871 in words is "twenty-eight million, seven hundred eighty-one thousand, eight hundred seventy-one".