21120005 has 8 divisors (see below), whose sum is σ = 25515000. Its totient is φ = 16782016.

The previous prime is 21119999. The next prime is 21120017. The reversal of 21120005 is 50002112.

It can be written as a sum of positive squares in 4 ways, for example, as 770884 + 20349121 = 878^2 + 4511^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21120005 is a prime.

It is a super-2 number, since 2×21120005² = 892109222400050, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13430 + ... + 14919.

It is an arithmetic number, because the mean of its divisors is an integer number (3189375).

Almost surely, 2^21120005 is an apocalyptic number.

It is an amenable number.

21120005 is a deficient number, since it is larger than the sum of its proper divisors (4394995).

21120005 is a wasteful number, since it uses less digits than its factorization.

21120005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28503.

The product of its (nonzero) digits is 20, while the sum is 11.

The square root of 21120005 is about 4595.6506612231. The cubic root of 21120005 is about 276.4169510137.

Adding to 21120005 its reverse (50002112), we get a palindrome (71122117).

The spelling of 21120005 in words is "twenty-one million, one hundred twenty thousand, five".