21215440031 has 4 divisors (see below), whose sum is σ = 21219736992. Its totient is φ = 21211143072.

The previous prime is 21215440019. The next prime is 21215440049. The reversal of 21215440031 is 13004451212.

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 21215440031 - 2²⁶ = 21148331167 is a prime.

It is a super-2 number, since 2×21215440031² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21215439979 and 21215440006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21215440231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2141066 + ... + 2150951.

It is an arithmetic number, because the mean of its divisors is an integer number (5304934248).

Almost surely, 2^21215440031 is an apocalyptic number.

21215440031 is a deficient number, since it is larger than the sum of its proper divisors (4296961).

21215440031 is an equidigital number, since it uses as much as digits as its factorization.

21215440031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4296960.

The product of its (nonzero) digits is 960, while the sum is 23.

Adding to 21215440031 its reverse (13004451212), we get a palindrome (34219891243).

The spelling of 21215440031 in words is "twenty-one billion, two hundred fifteen million, four hundred forty thousand, thirty-one".