21234556544 has 16 divisors (see below), whose sum is σ = 42303218370. Its totient is φ = 10617278208.

The previous prime is 21234556543. The next prime is 21234556613. The reversal of 21234556544 is 44565543212.

It can be written as a sum of positive squares in only one way, i.e., 21234318400 + 238144 = 145720^2 + 488^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is not an unprimeable number, because it can be changed into a prime (21234556543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82947359 + ... + 82947614.

Almost surely, 2^21234556544 is an apocalyptic number.

It is an amenable number.

21234556544 is a deficient number, since it is larger than the sum of its proper divisors (21068661826).

21234556544 is an equidigital number, since it uses as much as digits as its factorization.

21234556544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165894987 (or 165894975 counting only the distinct ones).

The product of its digits is 576000, while the sum is 41.

The spelling of 21234556544 in words is "twenty-one billion, two hundred thirty-four million, five hundred fifty-six thousand, five hundred forty-four".