28781986 has 8 divisors (see below), whose sum is σ = 45712620. Its totient is φ = 13544448.

The previous prime is 28781971. The next prime is 28782031. The reversal of 28781986 is 68918782.

It can be written as a sum of positive squares in 2 ways, for example, as 27888961 + 893025 = 5281^2 + 945^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

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, 423231 + ... + 423298.

Almost surely, 2^28781986 is an apocalyptic number.

28781986 is a deficient number, since it is larger than the sum of its proper divisors (16930634).

28781986 is a wasteful number, since it uses less digits than its factorization.

28781986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 846548.

The product of its digits is 387072, while the sum is 49.

The square root of 28781986 is about 5364.8845281143. The cubic root of 28781986 is about 306.4598508405.

The spelling of 28781986 in words is "twenty-eight million, seven hundred eighty-one thousand, nine hundred eighty-six".