21243544436 has 6 divisors (see below), whose sum is σ = 37176202770. Its totient is φ = 10621772216.

The previous prime is 21243544373. The next prime is 21243544481. The reversal of 21243544436 is 63444534212.

It can be written as a sum of positive squares in only one way, i.e., 18381936400 + 2861608036 = 135580^2 + 53494^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21243544436.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2655443051 + ... + 2655443058.

It is an arithmetic number, because the mean of its divisors is an integer number (6196033795).

Almost surely, 2^21243544436 is an apocalyptic number.

It is an amenable number.

21243544436 is a deficient number, since it is larger than the sum of its proper divisors (15932658334).

21243544436 is a wasteful number, since it uses less digits than its factorization.

21243544436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5310886113 (or 5310886111 counting only the distinct ones).

The product of its digits is 276480, while the sum is 38.

The spelling of 21243544436 in words is "twenty-one billion, two hundred forty-three million, five hundred forty-four thousand, four hundred thirty-six".