21121212210101 has 4 divisors (see below), whose sum is σ = 22363636457772. Its totient is φ = 19878787962432.

The previous prime is 21121212210053. The next prime is 21121212210107. The reversal of 21121212210101 is 10101221212112.

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 16085923047076 + 5035289163025 = 4010726^2 + 2243945^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121212210101 - 2¹⁰ = 21121212209077 is a prime.

It is a super-2 number, since 2×21121212210101² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 1242424247653 = 21121212210101 / (2 + 1 + 1 + 2 + 1 + 2 + 1 + 2 + 2 + 1 + 0 + 1 + 0 + 1).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21121212210101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121212210107) 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, 621212123810 + ... + 621212123843.

It is an arithmetic number, because the mean of its divisors is an integer number (5590909114443).

Almost surely, 2^{21121212210101} is an apocalyptic number.

It is an amenable number.

21121212210101 is a deficient number, since it is larger than the sum of its proper divisors (1242424247671).

21121212210101 is a wasteful number, since it uses less digits than its factorization.

21121212210101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1242424247670.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21121212210101 its reverse (10101221212112), we get a palindrome (31222433422213).

The spelling of 21121212210101 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twelve million, two hundred ten thousand, one hundred one".