21101011021 has 4 divisors (see below), whose sum is σ = 21415951552. Its totient is φ = 20786070492.

The previous prime is 21101010977. The next prime is 21101011033. The reversal of 21101011021 is 12011010112.

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 21101011021 - 2¹⁵ = 21100978253 is a prime.

It is a super-2 number, since 2×21101011021² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21101010989 and 21101011007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101015021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 157470165 + ... + 157470298.

It is an arithmetic number, because the mean of its divisors is an integer number (5353987888).

Almost surely, 2^21101011021 is an apocalyptic number.

It is an amenable number.

21101011021 is a deficient number, since it is larger than the sum of its proper divisors (314940531).

21101011021 is an equidigital number, since it uses as much as digits as its factorization.

21101011021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 314940530.

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

Adding to 21101011021 its reverse (12011010112), we get a palindrome (33112021133).

Subtracting from 21101011021 its reverse (12011010112), we obtain a palindrome (9090000909).

The spelling of 21101011021 in words is "twenty-one billion, one hundred one million, eleven thousand, twenty-one".