21185869 has 8 divisors (see below), whose sum is σ = 21633248. Its totient is φ = 20742480.

The previous prime is 21185839. The next prime is 21185873. The reversal of 21185869 is 96858112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21185869 - 2⁵ = 21185837 is a prime.

It is a super-2 number, since 2×21185869² = 897682090570322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21185839) 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 7 ways as a sum of consecutive naturals, for example, 11254 + ... + 13000.

It is an arithmetic number, because the mean of its divisors is an integer number (2704156).

Almost surely, 2^21185869 is an apocalyptic number.

It is an amenable number.

21185869 is a deficient number, since it is larger than the sum of its proper divisors (447379).

21185869 is a wasteful number, since it uses less digits than its factorization.

21185869 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1995.

The product of its digits is 34560, while the sum is 40.

The square root of 21185869 is about 4602.8109889501. The cubic root of 21185869 is about 276.7039937702.

The spelling of 21185869 in words is "twenty-one million, one hundred eighty-five thousand, eight hundred sixty-nine".