27721145 has 16 divisors (see below), whose sum is σ = 34195728. Its totient is φ = 21565440.

The previous prime is 27721139. The next prime is 27721147. The reversal of 27721145 is 54112772.

It can be written as a sum of positive squares in 8 ways, for example, as 10837264 + 16883881 = 3292^2 + 4109^2 .

It is not a de Polignac number, because 27721145 - 2⁶ = 27721081 is a prime.

It is a super-2 number, since 2×27721145² = 1536923760222050, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (27721147) 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 15 ways as a sum of consecutive naturals, for example, 29117 + ... + 30053.

It is an arithmetic number, because the mean of its divisors is an integer number (2137233).

Almost surely, 2^27721145 is an apocalyptic number.

It is an amenable number.

27721145 is a deficient number, since it is larger than the sum of its proper divisors (6474583).

27721145 is an equidigital number, since it uses as much as digits as its factorization.

27721145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1100.

The product of its digits is 3920, while the sum is 29.

The square root of 27721145 is about 5265.0873686958. The cubic root of 27721145 is about 302.6474749346.

It can be divided in two parts, 2772 and 1145, that multiplied together give a triangular number (3173940 = T₂₅₁₉).

The spelling of 27721145 in words is "twenty-seven million, seven hundred twenty-one thousand, one hundred forty-five".