21012340211 has 4 divisors (see below), whose sum is σ = 21069594912. Its totient is φ = 20955085512.

The previous prime is 21012340201. The next prime is 21012340213. The reversal of 21012340211 is 11204321012.

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 21012340211 - 2⁶ = 21012340147 is a prime.

It is a super-2 number, since 2×21012340211² (a number of 21 digits) contains 22 as substring.

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 21012340211.

It is not an unprimeable number, because it can be changed into a prime (21012340213) 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, 28626800 + ... + 28627533.

It is an arithmetic number, because the mean of its divisors is an integer number (5267398728).

Almost surely, 2^21012340211 is an apocalyptic number.

21012340211 is a deficient number, since it is larger than the sum of its proper divisors (57254701).

21012340211 is an equidigital number, since it uses as much as digits as its factorization.

21012340211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57254700.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21012340211 its reverse (11204321012), we get a palindrome (32216661223).

The spelling of 21012340211 in words is "twenty-one billion, twelve million, three hundred forty thousand, two hundred eleven".