28991601 has 14 divisors (see below), whose sum is σ = 43468610. Its totient is φ = 19327248.

The previous prime is 28991593. The next prime is 28991617. The reversal of 28991601 is 10619982.

It can be written as a sum of positive squares in only one way, i.e., 19847025 + 9144576 = 4455^2 + 3024^2 .

It is not a de Polignac number, because 28991601 - 2³ = 28991593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28991801) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 19156 + ... + 20613.

Almost surely, 2^28991601 is an apocalyptic number.

It is an amenable number.

28991601 is a deficient number, since it is larger than the sum of its proper divisors (14477009).

28991601 is an frugal number, since it uses more digits than its factorization.

28991601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39787 (or 39772 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 28991601 is about 5384.3849230901. The cubic root of 28991601 is about 307.2020194875.

It can be divided in two parts, 28991 and 601, that added together give a palindrome (29592).

The spelling of 28991601 in words is "twenty-eight million, nine hundred ninety-one thousand, six hundred one".