21001121010001 has 4 divisors (see below), whose sum is σ = 22910313829104. Its totient is φ = 19091928190900.

The previous prime is 21001121009977. The next prime is 21001121010011. The reversal of 21001121010001 is 10001012110012.

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 21001121010001 - 2⁵ = 21001121009969 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21001121010001.

It is not an unprimeable number, because it can be changed into a prime (21001121010011) 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, 954596409535 + ... + 954596409556.

It is an arithmetic number, because the mean of its divisors is an integer number (5727578457276).

Almost surely, 2^{21001121010001} is an apocalyptic number.

It is an amenable number.

21001121010001 is a deficient number, since it is larger than the sum of its proper divisors (1909192819103).

21001121010001 is a wasteful number, since it uses less digits than its factorization.

21001121010001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1909192819102.

The product of its (nonzero) digits is 4, while the sum is 10.

Adding to 21001121010001 its reverse (10001012110012), we get a palindrome (31002133120013).

It can be divided in two parts, 2100112 and 1010001, that added together give a palindrome (3110113).

The spelling of 21001121010001 in words is "twenty-one trillion, one billion, one hundred twenty-one million, ten thousand, one".