21001221101011 has 4 divisors (see below), whose sum is σ = 22106548527400. Its totient is φ = 19895893674624.

The previous prime is 21001221101009. The next prime is 21001221101033. The reversal of 21001221101011 is 11010112210012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21001221101011 - 2¹ = 21001221101009 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21001221100982 and 21001221101000.

It is not an unprimeable number, because it can be changed into a prime (21001221101911) 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, 552663713166 + ... + 552663713203.

It is an arithmetic number, because the mean of its divisors is an integer number (5526637131850).

Almost surely, 2^{21001221101011} is an apocalyptic number.

21001221101011 is a deficient number, since it is larger than the sum of its proper divisors (1105327426389).

21001221101011 is a wasteful number, since it uses less digits than its factorization.

21001221101011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1105327426388.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21001221101011 its reverse (11010112210012), we get a palindrome (32011333311023).

The spelling of 21001221101011 in words is "twenty-one trillion, one billion, two hundred twenty-one million, one hundred one thousand, eleven".