28991797 has 4 divisors (see below), whose sum is σ = 29698956. Its totient is φ = 28284640.

The previous prime is 28991791. The next prime is 28991801. The reversal of 28991797 is 79719982.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10407076 + 18584721 = 3226^2 + 4311^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28991797 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 (28991791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 353518 + ... + 353599.

It is an arithmetic number, because the mean of its divisors is an integer number (7424739).

Almost surely, 2^28991797 is an apocalyptic number.

It is an amenable number.

28991797 is a deficient number, since it is larger than the sum of its proper divisors (707159).

28991797 is an equidigital number, since it uses as much as digits as its factorization.

28991797 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 707158.

The product of its digits is 571536, while the sum is 52.

The square root of 28991797 is about 5384.4031238383. The cubic root of 28991797 is about 307.2027117737.

The spelling of 28991797 in words is "twenty-eight million, nine hundred ninety-one thousand, seven hundred ninety-seven".