21001022001221 has 8 divisors (see below), whose sum is σ = 21014051872704. Its totient is φ = 20987995795200.

The previous prime is 21001022001133. The next prime is 21001022001269. The reversal of 21001022001221 is 12210022010012.

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 21001022001221 - 2³⁴ = 20983842132037 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21001022001196 and 21001022001205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001022001821) 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, 10590821 + ... + 12416421.

It is an arithmetic number, because the mean of its divisors is an integer number (2626756484088).

Almost surely, 2^{21001022001221} is an apocalyptic number.

It is an amenable number.

21001022001221 is a deficient number, since it is larger than the sum of its proper divisors (13029871483).

21001022001221 is a wasteful number, since it uses less digits than its factorization.

21001022001221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1832731.

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

Adding to 21001022001221 its reverse (12210022010012), we get a palindrome (33211044011233).

The spelling of 21001022001221 in words is "twenty-one trillion, one billion, twenty-two million, one thousand, two hundred twenty-one".