28409991 has 8 divisors (see below), whose sum is σ = 39527040. Its totient is φ = 18116472.

The previous prime is 28409989. The next prime is 28409993. The reversal of 28409991 is 19990482.

It is an interprime number because it is at equal distance from previous prime (28409989) and next prime (28409993).

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

It is not a de Polignac number, because 28409991 - 2¹ = 28409989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28409993) 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, 205801 + ... + 205938.

It is an arithmetic number, because the mean of its divisors is an integer number (4940880).

Almost surely, 2^28409991 is an apocalyptic number.

28409991 is a deficient number, since it is larger than the sum of its proper divisors (11117049).

28409991 is a wasteful number, since it uses less digits than its factorization.

28409991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 411765.

The product of its (nonzero) digits is 46656, while the sum is 42.

The square root of 28409991 is about 5330.1023442332. The cubic root of 28409991 is about 305.1338335883.

The spelling of 28409991 in words is "twenty-eight million, four hundred nine thousand, nine hundred ninety-one".