21001021221021 has 32 divisors (see below), whose sum is σ = 28915899640320. Its totient is φ = 13549365849600.

The previous prime is 21001021220999. The next prime is 21001021221029. The reversal of 21001021221021 is 12012212010012.

It is not a de Polignac number, because 21001021221021 - 2²³ = 21001012832413 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001021221029) 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 31 ways as a sum of consecutive naturals, for example, 6257631 + ... + 9008883.

It is an arithmetic number, because the mean of its divisors is an integer number (903621863760).

Almost surely, 2^{21001021221021} is an apocalyptic number.

It is an amenable number.

21001021221021 is a deficient number, since it is larger than the sum of its proper divisors (7914878419299).

21001021221021 is a wasteful number, since it uses less digits than its factorization.

21001021221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2751797.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21001021221021 its reverse (12012212010012), we get a palindrome (33013233231033).

The spelling of 21001021221021 in words is "twenty-one trillion, one billion, twenty-one million, two hundred twenty-one thousand, twenty-one".