28391969 has 4 divisors (see below), whose sum is σ = 28510020. Its totient is φ = 28273920.

The previous prime is 28391953. The next prime is 28391971. The reversal of 28391969 is 96919382.

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 24127744 + 4264225 = 4912^2 + 2065^2 .

It is a cyclic number.

It is not a de Polignac number, because 28391969 - 2⁴ = 28391953 is a prime.

It is a super-2 number, since 2×28391969² = 1612207807393922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28391929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58664 + ... + 59145.

It is an arithmetic number, because the mean of its divisors is an integer number (7127505).

Almost surely, 2^28391969 is an apocalyptic number.

It is an amenable number.

28391969 is a deficient number, since it is larger than the sum of its proper divisors (118051).

28391969 is a wasteful number, since it uses less digits than its factorization.

28391969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118050.

The product of its digits is 209952, while the sum is 47.

The square root of 28391969 is about 5328.4114893653. The cubic root of 28391969 is about 305.0692989538.

The spelling of 28391969 in words is "twenty-eight million, three hundred ninety-one thousand, nine hundred sixty-nine".