21211220005 has 4 divisors (see below), whose sum is σ = 25453464012. Its totient is φ = 16968976000.

The previous prime is 21211219973. The next prime is 21211220021. The reversal of 21211220005 is 50002211212.

It is a happy number.

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 11430603396 + 9780616609 = 106914^2 + 98897^2 .

It is not a de Polignac number, because 21211220005 - 2⁵ = 21211219973 is a prime.

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 (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2121121996 + ... + 2121122005.

It is an arithmetic number, because the mean of its divisors is an integer number (6363366003).

Almost surely, 2^21211220005 is an apocalyptic number.

It is an amenable number.

21211220005 is a deficient number, since it is larger than the sum of its proper divisors (4242244007).

21211220005 is an equidigital number, since it uses as much as digits as its factorization.

21211220005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4242244006.

The product of its (nonzero) digits is 80, while the sum is 16.

Adding to 21211220005 its reverse (50002211212), we get a palindrome (71213431217).

The spelling of 21211220005 in words is "twenty-one billion, two hundred eleven million, two hundred twenty thousand, five".