28991097 has 24 divisors (see below), whose sum is σ = 43584840. Its totient is φ = 18547200.

The previous prime is 28991089. The next prime is 28991129. The reversal of 28991097 is 79019982.

It can be written as a sum of positive squares in 4 ways, for example, as 8415801 + 20575296 = 2901^2 + 4536^2 .

It is not a de Polignac number, because 28991097 - 2³ = 28991089 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28991087) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 72097 + ... + 72497.

It is an arithmetic number, because the mean of its divisors is an integer number (1816035).

Almost surely, 2^28991097 is an apocalyptic number.

It is an amenable number.

28991097 is a deficient number, since it is larger than the sum of its proper divisors (14593743).

28991097 is a wasteful number, since it uses less digits than its factorization.

28991097 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 713 (or 710 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 45.

The square root of 28991097 is about 5384.3381208836. The cubic root of 28991097 is about 307.2002393085.

The spelling of 28991097 in words is "twenty-eight million, nine hundred ninety-one thousand, ninety-seven".