21086285 has 32 divisors (see below), whose sum is σ = 29306880. Its totient is φ = 14414400.

The previous prime is 21086281. The next prime is 21086287. The reversal of 21086285 is 58268012.

It is not a de Polignac number, because 21086285 - 2² = 21086281 is a prime.

It is a super-3 number, since 3×21086285³ (a number of 23 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (32) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21086281) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 99830 + ... + 100040.

It is an arithmetic number, because the mean of its divisors is an integer number (915840).

Almost surely, 2^21086285 is an apocalyptic number.

It is an amenable number.

21086285 is a deficient number, since it is larger than the sum of its proper divisors (8220595).

21086285 is a wasteful number, since it uses less digits than its factorization.

21086285 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329.

The product of its (nonzero) digits is 7680, while the sum is 32.

The square root of 21086285 is about 4591.9805095405. The cubic root of 21086285 is about 276.2697644247.

It can be divided in two parts, 2 and 1086285, that multiplied together give a triangular number (2172570 = T₂₀₈₄).

The spelling of 21086285 in words is "twenty-one million, eighty-six thousand, two hundred eighty-five".