28691917 has 2 divisors, whose sum is σ = 28691918. Its totient is φ = 28691916.

The previous prime is 28691911. The next prime is 28691941. The reversal of 28691917 is 71919682.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16434916 + 12257001 = 4054^2 + 3501^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28691917 is a prime.

It is a super-2 number, since 2×28691917² = 1646452202269778, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28691911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14345958 + 14345959.

It is an arithmetic number, because the mean of its divisors is an integer number (14345959).

Almost surely, 2^28691917 is an apocalyptic number.

It is an amenable number.

28691917 is a deficient number, since it is larger than the sum of its proper divisors (1).

28691917 is an equidigital number, since it uses as much as digits as its factorization.

28691917 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54432, while the sum is 43.

The square root of 28691917 is about 5356.4836413453. The cubic root of 28691917 is about 306.1398430973.

It can be divided in two parts, 286 and 91917, that multiplied together give a palindrome (26288262).

The spelling of 28691917 in words is "twenty-eight million, six hundred ninety-one thousand, nine hundred seventeen".