28780231 has 4 divisors (see below), whose sum is σ = 30295000. Its totient is φ = 27265464.

The previous prime is 28780223. The next prime is 28780247. The reversal of 28780231 is 13208782.

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 28780231 - 2³ = 28780223 is a prime.

It is a super-2 number, since 2×28780231² = 1656603392826722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28780193 and 28780202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28780261) 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, 757356 + ... + 757393.

It is an arithmetic number, because the mean of its divisors is an integer number (7573750).

Almost surely, 2^28780231 is an apocalyptic number.

28780231 is a deficient number, since it is larger than the sum of its proper divisors (1514769).

28780231 is a wasteful number, since it uses less digits than its factorization.

28780231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1514768.

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 28780231 is about 5364.7209619886. The cubic root of 28780231 is about 306.4536218521.

The spelling of 28780231 in words is "twenty-eight million, seven hundred eighty thousand, two hundred thirty-one".