21420344211 has 16 divisors (see below), whose sum is σ = 33766060800. Its totient is φ = 11818120608.

The previous prime is 21420344207. The next prime is 21420344243. The reversal of 21420344211 is 11244302412.

It is not a de Polignac number, because 21420344211 - 2² = 21420344207 is a prime.

It is a super-2 number, since 2×21420344211² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21420344311) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17585881 + ... + 17587098.

It is an arithmetic number, because the mean of its divisors is an integer number (2110378800).

Almost surely, 2^21420344211 is an apocalyptic number.

21420344211 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21420344211 is a deficient number, since it is larger than the sum of its proper divisors (12345716589).

21420344211 is a wasteful number, since it uses less digits than its factorization.

21420344211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35173018.

The product of its (nonzero) digits is 1536, while the sum is 24.

Adding to 21420344211 its reverse (11244302412), we get a palindrome (32664646623).

The spelling of 21420344211 in words is "twenty-one billion, four hundred twenty million, three hundred forty-four thousand, two hundred eleven".