21120220210121 has 8 divisors (see below), whose sum is σ = 22362644478600. Its totient is φ = 19877802427648.

The previous prime is 21120220209967. The next prime is 21120220210147. The reversal of 21120220210121 is 12101202202112.

It can be written as a sum of positive squares in 4 ways, for example, as 286290273721 + 20833929936400 = 535061^2 + 4564420^2 .

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

It is not a de Polignac number, because 21120220210121 - 2³⁰ = 21119146468297 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

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 21120220210121.

It is not an unprimeable number, because it can be changed into a prime (21120220210181) 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, 6145655 + ... + 8944803.

It is an arithmetic number, because the mean of its divisors is an integer number (2795330559825).

Almost surely, 2^{21120220210121} is an apocalyptic number.

It is an amenable number.

21120220210121 is a deficient number, since it is larger than the sum of its proper divisors (1242424268479).

21120220210121 is a wasteful number, since it uses less digits than its factorization.

21120220210121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3243003.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21120220210121 its reverse (12101202202112), we get a palindrome (33221422412233).

The spelling of 21120220210121 in words is "twenty-one trillion, one hundred twenty billion, two hundred twenty million, two hundred ten thousand, one hundred twenty-one".