21021001212121 has 4 divisors (see below), whose sum is σ = 21021016072500. Its totient is φ = 21020986351744.

The previous prime is 21021001212109. The next prime is 21021001212161. The reversal of 21021001212121 is 12121210012012.

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 9129849006096 + 11891152206025 = 3021564^2 + 3448355^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021001212121 - 2⁵ = 21021001212089 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21021001212095 and 21021001212104.

It is not an unprimeable number, because it can be changed into a prime (21021001212161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5055316 + ... + 8221813.

It is an arithmetic number, because the mean of its divisors is an integer number (5255254018125).

Almost surely, 2^{21021001212121} is an apocalyptic number.

It is an amenable number.

21021001212121 is a deficient number, since it is larger than the sum of its proper divisors (14860379).

21021001212121 is a wasteful number, since it uses less digits than its factorization.

21021001212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14860378.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21021001212121 its reverse (12121210012012), we get a palindrome (33142211224133).

The spelling of 21021001212121 in words is "twenty-one trillion, twenty-one billion, one million, two hundred twelve thousand, one hundred twenty-one".