21000000000001 has 32 divisors (see below), whose sum is σ = 23296207575168. Its totient is φ = 18771352151040.

The previous prime is 20999999999987. The next prime is 21000000000013. The reversal of 21000000000001 is 10000000000012.

It is a cyclic number.

It is not a de Polignac number, because 21000000000001 - 2⁴³ = 12203906977793 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21000000000001.

It is not an unprimeable number, because it can be changed into a prime (21000000000901) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 120660295 + ... + 120834211.

It is an arithmetic number, because the mean of its divisors is an integer number (728006486724).

Almost surely, 2^{21000000000001} is an apocalyptic number.

It is an amenable number.

21000000000001 is a deficient number, since it is larger than the sum of its proper divisors (2296207575167).

21000000000001 is a wasteful number, since it uses less digits than its factorization.

21000000000001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174801.

The product of its (nonzero) digits is 2, while the sum is 4.

Adding to 21000000000001 its reverse (10000000000012), we get a palindrome (31000000000013).

It can be divided in two parts, 2 and 1000000000001, that multiplied together give a palindrome (2000000000002).

The spelling of 21000000000001 in words is "twenty-one trillion, one", and thus it is an aban number and an uban number.