28381157 has 4 divisors (see below), whose sum is σ = 32435616. Its totient is φ = 24326700.

The previous prime is 28381147. The next prime is 28381163. The reversal of 28381157 is 75118382.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75118382 = 2 ⋅37559191.

It is a cyclic number.

It is not a de Polignac number, because 28381157 - 2⁴ = 28381141 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28381127) 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, 2027219 + ... + 2027232.

It is an arithmetic number, because the mean of its divisors is an integer number (8108904).

Almost surely, 2^28381157 is an apocalyptic number.

It is an amenable number.

28381157 is a deficient number, since it is larger than the sum of its proper divisors (4054459).

28381157 is an equidigital number, since it uses as much as digits as its factorization.

28381157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4054458.

The product of its digits is 13440, while the sum is 35.

The square root of 28381157 is about 5327.3968314741. The cubic root of 28381157 is about 305.0305693628.

The spelling of 28381157 in words is "twenty-eight million, three hundred eighty-one thousand, one hundred fifty-seven".