21201210122111 has 4 divisors (see below), whose sum is σ = 22448340129312. Its totient is φ = 19954080114912.

The previous prime is 21201210122101. The next prime is 21201210122123. The reversal of 21201210122111 is 11122101210212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21201210122111 - 2⁴² = 16803163611007 is a prime.

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: 1247130007183 = 21201210122111 / (2 + 1 + 2 + 0 + 1 + 2 + 1 + 0 + 1 + 2 + 2 + 1 + 1 + 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 21201210122111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201210122101) 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, 623565003575 + ... + 623565003608.

It is an arithmetic number, because the mean of its divisors is an integer number (5612085032328).

Almost surely, 2^{21201210122111} is an apocalyptic number.

21201210122111 is a deficient number, since it is larger than the sum of its proper divisors (1247130007201).

21201210122111 is a wasteful number, since it uses less digits than its factorization.

21201210122111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1247130007200.

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

Adding to 21201210122111 its reverse (11122101210212), we get a palindrome (32323311332323).

The spelling of 21201210122111 in words is "twenty-one trillion, two hundred one billion, two hundred ten million, one hundred twenty-two thousand, one hundred eleven".