21020120121001 has 4 divisors (see below), whose sum is σ = 21020312312532. Its totient is φ = 21019927929472.

The previous prime is 21020120120981. The next prime is 21020120121037. The reversal of 21020120121001 is 10012102102012.

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 20425193291776 + 594926829225 = 4519424^2 + 771315^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020120121001 - 2⁴³ = 12224027098793 is a prime.

It is a super-2 number, since 2×21020120121001² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21020120127001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 95931616 + ... + 96150481.

It is an arithmetic number, because the mean of its divisors is an integer number (5255078078133).

Almost surely, 2^{21020120121001} is an apocalyptic number.

It is an amenable number.

21020120121001 is a deficient number, since it is larger than the sum of its proper divisors (192191531).

21020120121001 is a wasteful number, since it uses less digits than its factorization.

21020120121001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 192191530.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21020120121001 its reverse (10012102102012), we get a palindrome (31032222223013).

The spelling of 21020120121001 in words is "twenty-one trillion, twenty billion, one hundred twenty million, one hundred twenty-one thousand, one".