21351212211 has 32 divisors (see below), whose sum is σ = 34009907200. Its totient is φ = 11657636640.

The previous prime is 21351212167. The next prime is 21351212219. The reversal of 21351212211 is 11221215312.

It is not a de Polignac number, because 21351212211 - 2¹⁸ = 21350950067 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21351212219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 156151 + ... + 259008.

It is an arithmetic number, because the mean of its divisors is an integer number (1062809600).

Almost surely, 2^21351212211 is an apocalyptic number.

21351212211 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21351212211 is a deficient number, since it is larger than the sum of its proper divisors (12658694989).

21351212211 is a wasteful number, since it uses less digits than its factorization.

21351212211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 415279.

The product of its digits is 240, while the sum is 21.

Adding to 21351212211 its reverse (11221215312), we get a palindrome (32572427523).

The spelling of 21351212211 in words is "twenty-one billion, three hundred fifty-one million, two hundred twelve thousand, two hundred eleven".