21084231 has 32 divisors (see below), whose sum is σ = 33177600. Its totient is φ = 11662560.

The previous prime is 21084227. The next prime is 21084253. The reversal of 21084231 is 13248012.

21084231 = T₅ + T₆ + ... + T₅₀₁.

It is not a de Polignac number, because 21084231 - 2² = 21084227 is a prime.

It is a super-2 number, since 2×21084231² = 889089593722722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a junction number, because it is equal to n+sod(n) for n = 21084198 and 21084207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21084631) 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 31 ways as a sum of consecutive naturals, for example, 117700 + ... + 117878.

It is an arithmetic number, because the mean of its divisors is an integer number (1036800).

Almost surely, 2^21084231 is an apocalyptic number.

21084231 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21084231 is a deficient number, since it is larger than the sum of its proper divisors (12093369).

21084231 is a wasteful number, since it uses less digits than its factorization.

21084231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 339.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21084231 is about 4591.7568533188. The cubic root of 21084231 is about 276.2607937198.

The spelling of 21084231 in words is "twenty-one million, eighty-four thousand, two hundred thirty-one".