21311022011 has 4 divisors (see below), whose sum is σ = 21353390352. Its totient is φ = 21268653672.

The previous prime is 21311021999. The next prime is 21311022043. The reversal of 21311022011 is 11022011312.

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 21311022011 - 2¹⁸ = 21310759867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21311022091) 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, 21183416 + ... + 21184421.

It is an arithmetic number, because the mean of its divisors is an integer number (5338347588).

Almost surely, 2^21311022011 is an apocalyptic number.

21311022011 is a deficient number, since it is larger than the sum of its proper divisors (42368341).

21311022011 is an equidigital number, since it uses as much as digits as its factorization.

21311022011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42368340.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21311022011 its reverse (11022011312), we get a palindrome (32333033323).

The spelling of 21311022011 in words is "twenty-one billion, three hundred eleven million, twenty-two thousand, eleven".