21201521111101 has 4 divisors (see below), whose sum is σ = 22448669411772. Its totient is φ = 19954372810432.

The previous prime is 21201521111063. The next prime is 21201521111117. The reversal of 21201521111101 is 10111112510212.

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 15900355625625 + 5301165485476 = 3987525^2 + 2302426^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201521111101 - 2²¹ = 21201519013949 is a prime.

It is a super-2 number, since 2×21201521111101² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201521111191) 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, 623574150310 + ... + 623574150343.

It is an arithmetic number, because the mean of its divisors is an integer number (5612167352943).

Almost surely, 2^{21201521111101} is an apocalyptic number.

It is an amenable number.

21201521111101 is a deficient number, since it is larger than the sum of its proper divisors (1247148300671).

21201521111101 is a wasteful number, since it uses less digits than its factorization.

21201521111101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1247148300670.

The product of its (nonzero) digits is 40, while the sum is 19.

Adding to 21201521111101 its reverse (10111112510212), we get a palindrome (31312633621313).

The spelling of 21201521111101 in words is "twenty-one trillion, two hundred one billion, five hundred twenty-one million, one hundred eleven thousand, one hundred one".