21011011601 has 2 divisors, whose sum is σ = 21011011602. Its totient is φ = 21011011600.

The previous prime is 21011011591. The next prime is 21011011643. The reversal of 21011011601 is 10611011012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19009791376 + 2001220225 = 137876^2 + 44735^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011011601 - 2⁶ = 21011011537 is a prime.

It is not a weakly prime, because it can be changed into another prime (21011011201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505505800 + 10505505801.

It is an arithmetic number, because the mean of its divisors is an integer number (10505505801).

Almost surely, 2^21011011601 is an apocalyptic number.

It is an amenable number.

21011011601 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011011601 is an equidigital number, since it uses as much as digits as its factorization.

21011011601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12, while the sum is 14.

Adding to 21011011601 its reverse (10611011012), we get a palindrome (31622022613).

The spelling of 21011011601 in words is "twenty-one billion, eleven million, eleven thousand, six hundred one".