20213111231 has 4 divisors (see below), whose sum is σ = 21402117792. Its totient is φ = 19024104672.

The previous prime is 20213111213. The next prime is 20213111239. The reversal of 20213111231 is 13211131202.

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 20213111231 - 2¹⁸ = 20212849087 is a prime.

It is a super-2 number, since 2×20213111231² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 1189006543 = 20213111231 / (2 + 0 + 2 + 1 + 3 + 1 + 1 + 1 + 2 + 3 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20213111239) 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, 594503255 + ... + 594503288.

It is an arithmetic number, because the mean of its divisors is an integer number (5350529448).

Almost surely, 2^20213111231 is an apocalyptic number.

20213111231 is a deficient number, since it is larger than the sum of its proper divisors (1189006561).

20213111231 is a wasteful number, since it uses less digits than its factorization.

20213111231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1189006560.

The product of its (nonzero) digits is 72, while the sum is 17.

Adding to 20213111231 its reverse (13211131202), we get a palindrome (33424242433).

The spelling of 20213111231 in words is "twenty billion, two hundred thirteen million, one hundred eleven thousand, two hundred thirty-one".