21125011001 has 2 divisors, whose sum is σ = 21125011002. Its totient is φ = 21125011000.

The previous prime is 21125010979. The next prime is 21125011003. The reversal of 21125011001 is 10011052112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15989855401 + 5135155600 = 126451^2 + 71660^2 .

It is a cyclic number.

It is not a de Polignac number, because 21125011001 - 2¹⁰ = 21125009977 is a prime.

Together with 21125011003, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21125011003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10562505500 + 10562505501.

It is an arithmetic number, because the mean of its divisors is an integer number (10562505501).

Almost surely, 2^21125011001 is an apocalyptic number.

It is an amenable number.

21125011001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21125011001 is an equidigital number, since it uses as much as digits as its factorization.

21125011001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20, while the sum is 14.

Adding to 21125011001 its reverse (10011052112), we get a palindrome (31136063113).

The spelling of 21125011001 in words is "twenty-one billion, one hundred twenty-five million, eleven thousand, one".