21204042011 has 2 divisors, whose sum is σ = 21204042012. Its totient is φ = 21204042010.

The previous prime is 21204041983. The next prime is 21204042023. The reversal of 21204042011 is 11024040212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21204042011 is a prime.

It is a super-2 number, since 2×21204042011² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21204042031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10602021005 + 10602021006.

It is an arithmetic number, because the mean of its divisors is an integer number (10602021006).

Almost surely, 2^21204042011 is an apocalyptic number.

21204042011 is a deficient number, since it is larger than the sum of its proper divisors (1).

21204042011 is an equidigital number, since it uses as much as digits as its factorization.

21204042011 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21204042011 its reverse (11024040212), we get a palindrome (32228082223).

The spelling of 21204042011 in words is "twenty-one billion, two hundred four million, forty-two thousand, eleven".