21444423555 has 16 divisors (see below), whose sum is σ = 35238405024. Its totient is φ = 11127916800.

The previous prime is 21444423551. The next prime is 21444423563. The reversal of 21444423555 is 55532444412.

It is not a de Polignac number, because 21444423555 - 2² = 21444423551 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21444423551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19318746 + ... + 19319855.

It is an arithmetic number, because the mean of its divisors is an integer number (2202400314).

Almost surely, 2^21444423555 is an apocalyptic number.

21444423555 is a deficient number, since it is larger than the sum of its proper divisors (13793981469).

21444423555 is a wasteful number, since it uses less digits than its factorization.

21444423555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38638646.

The product of its digits is 384000, while the sum is 39.

Adding to 21444423555 its reverse (55532444412), we get a palindrome (76976867967).

The spelling of 21444423555 in words is "twenty-one billion, four hundred forty-four million, four hundred twenty-three thousand, five hundred fifty-five".