21001213231 has 8 divisors (see below), whose sum is σ = 21092924160. Its totient is φ = 20909580288.

The previous prime is 21001213217. The next prime is 21001213291. The reversal of 21001213231 is 13231210012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21001213231 - 2⁹ = 21001212719 is a prime.

It is a super-2 number, since 2×21001213231² (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 (21001213291) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 557175 + ... + 593671.

It is an arithmetic number, because the mean of its divisors is an integer number (2636615520).

Almost surely, 2^21001213231 is an apocalyptic number.

21001213231 is a deficient number, since it is larger than the sum of its proper divisors (91710929).

21001213231 is a wasteful number, since it uses less digits than its factorization.

21001213231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38993.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21001213231 its reverse (13231210012), we get a palindrome (34232423243).

It can be divided in two parts, 210012 and 13231, that multiplied together give a palindrome (2778668772).

The spelling of 21001213231 in words is "twenty-one billion, one million, two hundred thirteen thousand, two hundred thirty-one".