28405391 has 8 divisors (see below), whose sum is σ = 33874944. Its totient is φ = 23288760.

The previous prime is 28405367. The next prime is 28405409. The reversal of 28405391 is 19350482.

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

It is a cyclic number.

It is not a de Polignac number, because 28405391 - 2¹⁴ = 28389007 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28405591) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 88055 + ... + 88376.

It is an arithmetic number, because the mean of its divisors is an integer number (4234368).

Almost surely, 2^28405391 is an apocalyptic number.

28405391 is a deficient number, since it is larger than the sum of its proper divisors (5469553).

28405391 is a wasteful number, since it uses less digits than its factorization.

28405391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176461.

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 28405391 is about 5329.6708153506. The cubic root of 28405391 is about 305.1173641310.

The spelling of 28405391 in words is "twenty-eight million, four hundred five thousand, three hundred ninety-one".