21151105 has 4 divisors (see below), whose sum is σ = 25381332. Its totient is φ = 16920880.

The previous prime is 21151069. The next prime is 21151147. The reversal of 21151105 is 50115112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6885376 + 14265729 = 2624^2 + 3777^2 .

It is not a de Polignac number, because 21151105 - 2¹¹ = 21149057 is a prime.

It is a Duffinian 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 3 ways as a sum of consecutive naturals, for example, 2115106 + ... + 2115115.

It is an arithmetic number, because the mean of its divisors is an integer number (6345333).

Almost surely, 2^21151105 is an apocalyptic number.

It is an amenable number.

21151105 is a deficient number, since it is larger than the sum of its proper divisors (4230227).

21151105 is an equidigital number, since it uses as much as digits as its factorization.

21151105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4230226.

The product of its (nonzero) digits is 50, while the sum is 16.

The square root of 21151105 is about 4599.0330505444. The cubic root of 21151105 is about 276.5525625825.

Adding to 21151105 its reverse (50115112), we get a palindrome (71266217).

The spelling of 21151105 in words is "twenty-one million, one hundred fifty-one thousand, one hundred five".