21123021211 has 24 divisors (see below), whose sum is σ = 22221814752. Its totient is φ = 20073715200.

The previous prime is 21123021197. The next prime is 21123021217. The reversal of 21123021211 is 11212032112.

It is not a de Polignac number, because 21123021211 - 2¹³ = 21123013019 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21123021217) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 24085105 + ... + 24085981.

It is an arithmetic number, because the mean of its divisors is an integer number (925908948).

Almost surely, 2^21123021211 is an apocalyptic number.

21123021211 is a deficient number, since it is larger than the sum of its proper divisors (1098793541).

21123021211 is an equidigital number, since it uses as much as digits as its factorization.

21123021211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1363 (or 1332 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 21123021211 its reverse (11212032112), we get a palindrome (32335053323).

The spelling of 21123021211 in words is "twenty-one billion, one hundred twenty-three million, twenty-one thousand, two hundred eleven".