21161005 has 16 divisors (see below), whose sum is σ = 27024624. Its totient is φ = 15851520.

The previous prime is 21160973. The next prime is 21161017. The reversal of 21161005 is 50016112.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 5008644 + 16152361 = 2238^2 + 4019^2 .

It is not a de Polignac number, because 21161005 - 2⁵ = 21160973 is a prime.

It is a super-2 number, since 2×21161005² = 895576265220050, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21161005.

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 15 ways as a sum of consecutive naturals, for example, 19969 + ... + 21001.

It is an arithmetic number, because the mean of its divisors is an integer number (1689039).

Almost surely, 2^21161005 is an apocalyptic number.

It is an amenable number.

21161005 is a deficient number, since it is larger than the sum of its proper divisors (5863619).

21161005 is a wasteful number, since it uses less digits than its factorization.

21161005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1296.

The product of its (nonzero) digits is 60, while the sum is 16.

The square root of 21161005 is about 4600.1092378334. The cubic root of 21161005 is about 276.5957036432.

Adding to 21161005 its reverse (50016112), we get a palindrome (71177117).

It can be divided in two parts, 211 and 61005, that added together give a palindrome (61216).

The spelling of 21161005 in words is "twenty-one million, one hundred sixty-one thousand, five".