28275391 has 4 divisors (see below), whose sum is σ = 28738984. Its totient is φ = 27811800.

The previous prime is 28275371. The next prime is 28275409. The reversal of 28275391 is 19357282.

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 28275391 - 2²¹ = 26178239 is a prime.

It is a super-3 number, since 3×28275391³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28275391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28275371) 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, 231705 + ... + 231826.

It is an arithmetic number, because the mean of its divisors is an integer number (7184746).

Almost surely, 2^28275391 is an apocalyptic number.

28275391 is a deficient number, since it is larger than the sum of its proper divisors (463593).

28275391 is an equidigital number, since it uses as much as digits as its factorization.

28275391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 463592.

The product of its digits is 30240, while the sum is 37.

The square root of 28275391 is about 5317.4609542525. The cubic root of 28275391 is about 304.6511859294.

The spelling of 28275391 in words is "twenty-eight million, two hundred seventy-five thousand, three hundred ninety-one".