28165121 has 4 divisors (see below), whose sum is σ = 28250544. Its totient is φ = 28079700.

The previous prime is 28165117. The next prime is 28165147. The reversal of 28165121 is 12156182.

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: 12156182 = 2 ⋅6078091.

It is a cyclic number.

It is not a de Polignac number, because 28165121 - 2² = 28165117 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28165021) 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, 42215 + ... + 42876.

It is an arithmetic number, because the mean of its divisors is an integer number (7062636).

Almost surely, 2^28165121 is an apocalyptic number.

It is an amenable number.

28165121 is a deficient number, since it is larger than the sum of its proper divisors (85423).

28165121 is an equidigital number, since it uses as much as digits as its factorization.

28165121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85422.

The product of its digits is 960, while the sum is 26.

The square root of 28165121 is about 5307.0821550076. The cubic root of 28165121 is about 304.2546379018.

The spelling of 28165121 in words is "twenty-eight million, one hundred sixty-five thousand, one hundred twenty-one".