21185969 has 8 divisors (see below), whose sum is σ = 25487040. Its totient is φ = 17203536.

The previous prime is 21185953. The next prime is 21185981. The reversal of 21185969 is 96958112.

It is a happy number.

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

It is not a de Polignac number, because 21185969 - 2⁴ = 21185953 is a prime.

It is a super-2 number, since 2×21185969² = 897690564937922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21185939) 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, 79514 + ... + 79779.

It is an arithmetic number, because the mean of its divisors is an integer number (3185880).

Almost surely, 2^21185969 is an apocalyptic number.

It is an amenable number.

21185969 is a deficient number, since it is larger than the sum of its proper divisors (4301071).

21185969 is a wasteful number, since it uses less digits than its factorization.

21185969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159319.

The product of its digits is 38880, while the sum is 41.

The square root of 21185969 is about 4602.8218518644. The cubic root of 21185969 is about 276.7044291289.

The spelling of 21185969 in words is "twenty-one million, one hundred eighty-five thousand, nine hundred sixty-nine".