21142165 has 8 divisors (see below), whose sum is σ = 27677088. Its totient is φ = 15376080.

The previous prime is 21142153. The next prime is 21142171. The reversal of 21142165 is 56124112.

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

It is not a de Polignac number, because 21142165 - 2¹⁵ = 21109397 is a prime.

It is a super-2 number, since 2×21142165² = 893982281774450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 192147 + ... + 192256.

It is an arithmetic number, because the mean of its divisors is an integer number (3459636).

Almost surely, 2^21142165 is an apocalyptic number.

It is an amenable number.

21142165 is a deficient number, since it is larger than the sum of its proper divisors (6534923).

21142165 is a wasteful number, since it uses less digits than its factorization.

21142165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 384419.

The product of its digits is 480, while the sum is 22.

The square root of 21142165 is about 4598.0610043800. The cubic root of 21142165 is about 276.5135933288.

Adding to 21142165 its reverse (56124112), we get a palindrome (77266277).

The spelling of 21142165 in words is "twenty-one million, one hundred forty-two thousand, one hundred sixty-five".