21513231444 has 24 divisors (see below), whose sum is σ = 51364925920. Its totient is φ = 7004307744.

The previous prime is 21513231413. The next prime is 21513231449. The reversal of 21513231444 is 44413231512.

It is a super-2 number, since 2×21513231444² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513231449) 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, 20845639 + ... + 20846670.

Almost surely, 2^21513231444 is an apocalyptic number.

It is an amenable number.

21513231444 is an abundant number, since it is smaller than the sum of its proper divisors (29851694476).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21513231444 is a wasteful number, since it uses less digits than its factorization.

21513231444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41692359 (or 41692357 counting only the distinct ones).

The product of its digits is 11520, while the sum is 30.

Adding to 21513231444 its reverse (44413231512), we get a palindrome (65926462956).

The spelling of 21513231444 in words is "twenty-one billion, five hundred thirteen million, two hundred thirty-one thousand, four hundred forty-four".