21211020100121 has 4 divisors (see below), whose sum is σ = 22458727164852. Its totient is φ = 19963313035392.

The previous prime is 21211020100111. The next prime is 21211020100157. The reversal of 21211020100121 is 12100102011212.

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 9841553265625 + 11369466834496 = 3137125^2 + 3371864^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211020100121 - 2²² = 21211015905817 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21211020100096 and 21211020100105.

It is not an unprimeable number, because it can be changed into a prime (21211020100111) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 623853532340 + ... + 623853532373.

It is an arithmetic number, because the mean of its divisors is an integer number (5614681791213).

Almost surely, 2^{21211020100121} is an apocalyptic number.

It is an amenable number.

21211020100121 is a deficient number, since it is larger than the sum of its proper divisors (1247707064731).

21211020100121 is a wasteful number, since it uses less digits than its factorization.

21211020100121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1247707064730.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21211020100121 its reverse (12100102011212), we get a palindrome (33311122111333).

The spelling of 21211020100121 in words is "twenty-one trillion, two hundred eleven billion, twenty million, one hundred thousand, one hundred twenty-one".