21211021021 has 4 divisors (see below), whose sum is σ = 21372937344. Its totient is φ = 21049104700.

The previous prime is 21211021003. The next prime is 21211021081. The reversal of 21211021021 is 12012011212.

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 21211021021 - 2²³ = 21202632413 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21211020992 and 21211021010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211021081) 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, 80957965 + ... + 80958226.

It is an arithmetic number, because the mean of its divisors is an integer number (5343234336).

Almost surely, 2^21211021021 is an apocalyptic number.

It is an amenable number.

21211021021 is a deficient number, since it is larger than the sum of its proper divisors (161916323).

21211021021 is a wasteful number, since it uses less digits than its factorization.

21211021021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161916322.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21211021021 its reverse (12012011212), we get a palindrome (33223032233).

The spelling of 21211021021 in words is "twenty-one billion, two hundred eleven million, twenty-one thousand, twenty-one".