21001113544 has 8 divisors (see below), whose sum is σ = 39377087910. Its totient is φ = 10500556768.

The previous prime is 21001113533. The next prime is 21001113559. The reversal of 21001113544 is 44531110012.

It can be written as a sum of positive squares in only one way, i.e., 12091641444 + 8909472100 = 109962^2 + 94390^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1312569589 + ... + 1312569604.

Almost surely, 2^21001113544 is an apocalyptic number.

It is an amenable number.

21001113544 is a deficient number, since it is larger than the sum of its proper divisors (18375974366).

21001113544 is a wasteful number, since it uses less digits than its factorization.

21001113544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2625139199 (or 2625139195 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

Adding to 21001113544 its reverse (44531110012), we get a palindrome (65532223556).

The spelling of 21001113544 in words is "twenty-one billion, one million, one hundred thirteen thousand, five hundred forty-four".