21289185 has 36 divisors (see below), whose sum is σ = 39223548. Its totient is φ = 10679808.

The previous prime is 21289181. The next prime is 21289187. The reversal of 21289185 is 58198212.

It can be written as a sum of positive squares in 6 ways, for example, as 138384 + 21150801 = 372^2 + 4599^2 .

It is not a de Polignac number, because 21289185 - 2² = 21289181 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21289181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 12187 + ... + 13823.

It is an arithmetic number, because the mean of its divisors is an integer number (1089543).

Almost surely, 2^21289185 is an apocalyptic number.

It is an amenable number.

21289185 is a deficient number, since it is larger than the sum of its proper divisors (17934363).

21289185 is a wasteful number, since it uses less digits than its factorization.

21289185 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1682 (or 1662 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The square root of 21289185 is about 4614.0204810989. The cubic root of 21289185 is about 277.1530604602.

The spelling of 21289185 in words is "twenty-one million, two hundred eighty-nine thousand, one hundred eighty-five".