28171961 has 4 divisors (see below), whose sum is σ = 28859124. Its totient is φ = 27484800.

The previous prime is 28171951. The next prime is 28171967. The reversal of 28171961 is 16917182.

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 3171961 + 25000000 = 1781^2 + 5000^2 .

It is a cyclic number.

It is not a de Polignac number, because 28171961 - 2¹⁰ = 28170937 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28171967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 343520 + ... + 343601.

It is an arithmetic number, because the mean of its divisors is an integer number (7214781).

Almost surely, 2^28171961 is an apocalyptic number.

It is an amenable number.

28171961 is a deficient number, since it is larger than the sum of its proper divisors (687163).

28171961 is an equidigital number, since it uses as much as digits as its factorization.

28171961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 687162.

The product of its digits is 6048, while the sum is 35.

The square root of 28171961 is about 5307.7265377937. The cubic root of 28171961 is about 304.2792656826.

The spelling of 28171961 in words is "twenty-eight million, one hundred seventy-one thousand, nine hundred sixty-one".