28691901 has 30 divisors (see below), whose sum is σ = 49865310. Its totient is φ = 16393104.

The previous prime is 28691893. The next prime is 28691911. The reversal of 28691901 is 10919682.

It can be written as a sum of positive squares in only one way, i.e., 28676025 + 15876 = 5355^2 + 126^2 .

It is not a de Polignac number, because 28691901 - 2³ = 28691893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28691911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 355 + ... + 7583.

It is an arithmetic number, because the mean of its divisors is an integer number (1662177).

Almost surely, 2^28691901 is an apocalyptic number.

28691901 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28691901 is a deficient number, since it is larger than the sum of its proper divisors (21173409).

28691901 is an equidigital number, since it uses as much as digits as its factorization.

28691901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7255 (or 7239 counting only the distinct ones).

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

The square root of 28691901 is about 5356.4821478280. The cubic root of 28691901 is about 306.1397861912.

It can be divided in two parts, 28691 and 901, that added together give a palindrome (29592).

The spelling of 28691901 in words is "twenty-eight million, six hundred ninety-one thousand, nine hundred one".