21203111005 has 4 divisors (see below), whose sum is σ = 25443733212. Its totient is φ = 16962488800.

The previous prime is 21203111003. The next prime is 21203111029. The reversal of 21203111005 is 50011130212.

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 10545852249 + 10657258756 = 102693^2 + 103234^2 .

It is not a de Polignac number, because 21203111005 - 2¹ = 21203111003 is a prime.

It is a super-2 number, since 2×21203111005² (a number of 21 digits) 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 21203111005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21203111003) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2120311096 + ... + 2120311105.

It is an arithmetic number, because the mean of its divisors is an integer number (6360933303).

Almost surely, 2^21203111005 is an apocalyptic number.

It is an amenable number.

21203111005 is a deficient number, since it is larger than the sum of its proper divisors (4240622207).

21203111005 is an equidigital number, since it uses as much as digits as its factorization.

21203111005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4240622206.

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

Adding to 21203111005 its reverse (50011130212), we get a palindrome (71214241217).

The spelling of 21203111005 in words is "twenty-one billion, two hundred three million, one hundred eleven thousand, five".