21011201001001 has 4 divisors (see below), whose sum is σ = 21011449641732. Its totient is φ = 21010952360272.

The previous prime is 21011201000899. The next prime is 21011201001013. The reversal of 21011201001001 is 10010010211012.

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 696565506025 + 20314635494976 = 834605^2 + 4507176^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011201001001 - 2³⁵ = 20976841262633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21011201101001) 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 in 3 ways as a sum of consecutive naturals, for example, 124193566 + ... + 124362631.

It is an arithmetic number, because the mean of its divisors is an integer number (5252862410433).

Almost surely, 2^{21011201001001} is an apocalyptic number.

It is an amenable number.

21011201001001 is a deficient number, since it is larger than the sum of its proper divisors (248640731).

21011201001001 is an equidigital number, since it uses as much as digits as its factorization.

21011201001001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248640730.

The product of its (nonzero) digits is 4, while the sum is 10.

Adding to 21011201001001 its reverse (10010010211012), we get a palindrome (31021211212013).

The spelling of 21011201001001 in words is "twenty-one trillion, eleven billion, two hundred one million, one thousand, one".