21084165 has 32 divisors (see below), whose sum is σ = 39692160. Its totient is φ = 10582272.

The previous prime is 21084139. The next prime is 21084187. The reversal of 21084165 is 56148012.

It is not a de Polignac number, because 21084165 - 2¹² = 21080069 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2299 + ... + 6888.

It is an arithmetic number, because the mean of its divisors is an integer number (1240380).

Almost surely, 2^21084165 is an apocalyptic number.

It is an amenable number.

21084165 is a deficient number, since it is larger than the sum of its proper divisors (18607995).

21084165 is a wasteful number, since it uses less digits than its factorization.

21084165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9218 (or 9212 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21084165 is about 4591.7496665215. The cubic root of 21084165 is about 276.2605054596.

The spelling of 21084165 in words is "twenty-one million, eighty-four thousand, one hundred sixty-five".