21131213444 has 48 divisors (see below), whose sum is σ = 40537215936. Its totient is φ = 9558595200.

The previous prime is 21131213443. The next prime is 21131213447. The reversal of 21131213444 is 44431213112.

It is a super-2 number, since 2×21131213444² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21131213443) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11257034 + ... + 11258910.

It is an arithmetic number, because the mean of its divisors is an integer number (844525332).

Almost surely, 2^21131213444 is an apocalyptic number.

It is an amenable number.

21131213444 is a deficient number, since it is larger than the sum of its proper divisors (19406002492).

21131213444 is a wasteful number, since it uses less digits than its factorization.

21131213444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2996 (or 2994 counting only the distinct ones).

The product of its digits is 2304, while the sum is 26.

Adding to 21131213444 its reverse (44431213112), we get a palindrome (65562426556).

The spelling of 21131213444 in words is "twenty-one billion, one hundred thirty-one million, two hundred thirteen thousand, four hundred forty-four".