21201100121 has 8 divisors (see below), whose sum is σ = 21685185864. Its totient is φ = 20720128000.

The previous prime is 21201100111. The next prime is 21201100127. The reversal of 21201100121 is 12100110212.

It can be written as a sum of positive squares in 4 ways, for example, as 4989444496 + 16211655625 = 70636^2 + 127325^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21201100121 - 2³⁰ = 20127358297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21201100127) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 764630 + ... + 791871.

It is an arithmetic number, because the mean of its divisors is an integer number (2710648233).

Almost surely, 2^21201100121 is an apocalyptic number.

It is an amenable number.

21201100121 is a deficient number, since it is larger than the sum of its proper divisors (484085743).

21201100121 is a wasteful number, since it uses less digits than its factorization.

21201100121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1556811.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21201100121 its reverse (12100110212), we get a palindrome (33301210333).

The spelling of 21201100121 in words is "twenty-one billion, two hundred one million, one hundred thousand, one hundred twenty-one".