28191947 has 4 divisors (see below), whose sum is σ = 32219376. Its totient is φ = 24164520.

The previous prime is 28191941. The next prime is 28191949. The reversal of 28191947 is 74919182.

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 28191947 - 2⁴ = 28191931 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28191941) 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, 2013704 + ... + 2013717.

It is an arithmetic number, because the mean of its divisors is an integer number (8054844).

Almost surely, 2^28191947 is an apocalyptic number.

28191947 is a deficient number, since it is larger than the sum of its proper divisors (4027429).

28191947 is an equidigital number, since it uses as much as digits as its factorization.

28191947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4027428.

The product of its digits is 36288, while the sum is 41.

The square root of 28191947 is about 5309.6089309854. The cubic root of 28191947 is about 304.3512034967.

The spelling of 28191947 in words is "twenty-eight million, one hundred ninety-one thousand, nine hundred forty-seven".