21201221002001 has 4 divisors (see below), whose sum is σ = 21202669286400. Its totient is φ = 21199772717604.

The previous prime is 21201221001977. The next prime is 21201221002051. The reversal of 21201221002001 is 10020012210212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21201221002001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21201221002051) 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, 724120241 + ... + 724149518.

It is an arithmetic number, because the mean of its divisors is an integer number (5300667321600).

Almost surely, 2^{21201221002001} is an apocalyptic number.

It is an amenable number.

21201221002001 is a deficient number, since it is larger than the sum of its proper divisors (1448284399).

21201221002001 is a wasteful number, since it uses less digits than its factorization.

21201221002001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1448284398.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21201221002001 its reverse (10020012210212), we get a palindrome (31221233212213).

The spelling of 21201221002001 in words is "twenty-one trillion, two hundred one billion, two hundred twenty-one million, two thousand, one".