21186669 has 24 divisors (see below), whose sum is σ = 33209568. Its totient is φ = 11978400.

The previous prime is 21186637. The next prime is 21186677. The reversal of 21186669 is 96668112.

It is not a de Polignac number, because 21186669 - 2⁵ = 21186637 is a prime.

It is a super-2 number, since 2×21186669² = 897749886631122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21186629) 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 23 ways as a sum of consecutive naturals, for example, 14134 + ... + 15560.

It is an arithmetic number, because the mean of its divisors is an integer number (1383732).

Almost surely, 2^21186669 is an apocalyptic number.

It is an amenable number.

21186669 is a deficient number, since it is larger than the sum of its proper divisors (12022899).

21186669 is a wasteful number, since it uses less digits than its factorization.

21186669 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1545 (or 1538 counting only the distinct ones).

The product of its digits is 31104, while the sum is 39.

The square root of 21186669 is about 4602.8978915462. The cubic root of 21186669 is about 276.7074766013.

The spelling of 21186669 in words is "twenty-one million, one hundred eighty-six thousand, six hundred sixty-nine".