28291913 has 4 divisors (see below), whose sum is σ = 30468228. Its totient is φ = 26115600.

The previous prime is 28291897. The next prime is 28291973. The reversal of 28291913 is 31919282.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31919282 = 2 ⋅15959641.

It can be written as a sum of positive squares in 2 ways, for example, as 19123129 + 9168784 = 4373^2 + 3028^2 .

It is a cyclic number.

It is not a de Polignac number, because 28291913 - 2⁴ = 28291897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28291973) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1088138 + ... + 1088163.

It is an arithmetic number, because the mean of its divisors is an integer number (7617057).

Almost surely, 2^28291913 is an apocalyptic number.

It is an amenable number.

28291913 is a deficient number, since it is larger than the sum of its proper divisors (2176315).

28291913 is a wasteful number, since it uses less digits than its factorization.

28291913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2176314.

The product of its digits is 7776, while the sum is 35.

The square root of 28291913 is about 5319.0142883809. The cubic root of 28291913 is about 304.7105127462.

The spelling of 28291913 in words is "twenty-eight million, two hundred ninety-one thousand, nine hundred thirteen".