28406891 has 4 divisors (see below), whose sum is σ = 29099784. Its totient is φ = 27714000.

The previous prime is 28406879. The next prime is 28406923. The reversal of 28406891 is 19860482.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28406891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28406801) 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, 346385 + ... + 346466.

It is an arithmetic number, because the mean of its divisors is an integer number (7274946).

Almost surely, 2^28406891 is an apocalyptic number.

28406891 is a deficient number, since it is larger than the sum of its proper divisors (692893).

28406891 is an equidigital number, since it uses as much as digits as its factorization.

28406891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 692892.

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 28406891 is about 5329.8115351295. The cubic root of 28406891 is about 305.1227348016.

The spelling of 28406891 in words is "twenty-eight million, four hundred six thousand, eight hundred ninety-one".