21011222231 has 4 divisors (see below), whose sum is σ = 21012768600. Its totient is φ = 21009675864.

The previous prime is 21011222213. The next prime is 21011222279. The reversal of 21011222231 is 13222211012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21011222231 is a prime.

It is a super-2 number, since 2×21011222231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011222201) 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, 752621 + ... + 780038.

It is an arithmetic number, because the mean of its divisors is an integer number (5253192150).

Almost surely, 2^21011222231 is an apocalyptic number.

21011222231 is a deficient number, since it is larger than the sum of its proper divisors (1546369).

21011222231 is a wasteful number, since it uses less digits than its factorization.

21011222231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1546368.

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

Adding to 21011222231 its reverse (13222211012), we get a palindrome (34233433243).

The spelling of 21011222231 in words is "twenty-one billion, eleven million, two hundred twenty-two thousand, two hundred thirty-one".