21121201002001 has 4 divisors (see below), whose sum is σ = 22363624590372. Its totient is φ = 19878777413632.

The previous prime is 21121201001977. The next prime is 21121201002029. The reversal of 21121201002001 is 10020010212112.

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 12397448042001 + 8723752960000 = 3521001^2 + 2953600^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121201002001 - 2¹⁷ = 21121200870929 is a prime.

It is a super-2 number, since 2×21121201002001² (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 (21121201002091) 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, 621211794160 + ... + 621211794193.

It is an arithmetic number, because the mean of its divisors is an integer number (5590906147593).

Almost surely, 2^{21121201002001} is an apocalyptic number.

It is an amenable number.

21121201002001 is a deficient number, since it is larger than the sum of its proper divisors (1242423588371).

21121201002001 is a wasteful number, since it uses less digits than its factorization.

21121201002001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1242423588370.

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

Adding to 21121201002001 its reverse (10020010212112), we get a palindrome (31141211214113).

The spelling of 21121201002001 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred one million, two thousand, one".