21001220102021 has 4 divisors (see below), whose sum is σ = 21006207334944. Its totient is φ = 20996232869100.

The previous prime is 21001220102003. The next prime is 21001220102053. The reversal of 21001220102021 is 12020102210012.

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 not a de Polignac number, because 21001220102021 - 2⁶ = 21001220101957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21001220101987 and 21001220102005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001220102221) 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, 2493610145 + ... + 2493618566.

It is an arithmetic number, because the mean of its divisors is an integer number (5251551833736).

Almost surely, 2^{21001220102021} is an apocalyptic number.

It is an amenable number.

21001220102021 is a deficient number, since it is larger than the sum of its proper divisors (4987232923).

21001220102021 is an equidigital number, since it uses as much as digits as its factorization.

21001220102021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4987232922.

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

Adding to 21001220102021 its reverse (12020102210012), we get a palindrome (33021322312033).

The spelling of 21001220102021 in words is "twenty-one trillion, one billion, two hundred twenty million, one hundred two thousand, twenty-one".