21231220311 has 56 divisors (see below), whose sum is σ = 36427643904. Its totient is φ = 12116154960.

The previous prime is 21231220291. The next prime is 21231220343. The reversal of 21231220311 is 11302213212.

21231220311 is a `hidden beast` number, since 21 + 2 + 312 + 20 + 311 = 666.

It is not a de Polignac number, because 21231220311 - 2¹⁷ = 21231089239 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21231220111) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 4646550 + ... + 4651116.

Almost surely, 2^21231220311 is an apocalyptic number.

21231220311 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21231220311 is a deficient number, since it is larger than the sum of its proper divisors (15196423593).

21231220311 is an frugal number, since it uses more digits than its factorization.

21231220311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5503 (or 5488 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21231220311 its reverse (11302213212), we get a palindrome (32533433523).

The spelling of 21231220311 in words is "twenty-one billion, two hundred thirty-one million, two hundred twenty thousand, three hundred eleven".