21202000100021 has 4 divisors (see below), whose sum is σ = 22832923184652. Its totient is φ = 19571077015392.

The previous prime is 21202000100009. The next prime is 21202000100023. The reversal of 21202000100021 is 12000100020212.

It is a happy number.

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 14302389422500 + 6899610677521 = 3781850^2 + 2626711^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202000100021 - 2¹⁸ = 21201999837877 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21202000099975 and 21202000100011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202000100023) 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, 815461542296 + ... + 815461542321.

It is an arithmetic number, because the mean of its divisors is an integer number (5708230796163).

Almost surely, 2^{21202000100021} is an apocalyptic number.

It is an amenable number.

21202000100021 is a deficient number, since it is larger than the sum of its proper divisors (1630923084631).

21202000100021 is a wasteful number, since it uses less digits than its factorization.

21202000100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1630923084630.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21202000100021 its reverse (12000100020212), we get a palindrome (33202100120233).

The spelling of 21202000100021 in words is "twenty-one trillion, two hundred two billion, one hundred thousand, twenty-one".