21001012231 has 4 divisors (see below), whose sum is σ = 21107616552. Its totient is φ = 20894407912.

The previous prime is 21001012199. The next prime is 21001012243. The reversal of 21001012231 is 13221010012.

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 21001012231 - 2⁵ = 21001012199 is a prime.

It is a super-3 number, since 3×21001012231³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001012261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53301865 + ... + 53302258.

It is an arithmetic number, because the mean of its divisors is an integer number (5276904138).

Almost surely, 2^21001012231 is an apocalyptic number.

21001012231 is a deficient number, since it is larger than the sum of its proper divisors (106604321).

21001012231 is a wasteful number, since it uses less digits than its factorization.

21001012231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106604320.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21001012231 its reverse (13221010012), we get a palindrome (34222022243).

The spelling of 21001012231 in words is "twenty-one billion, one million, twelve thousand, two hundred thirty-one".