21244020555 has 64 divisors (see below), whose sum is σ = 36525196800. Its totient is φ = 10511493120.

The previous prime is 21244020463. The next prime is 21244020569. The reversal of 21244020555 is 55502044212.

It is not a de Polignac number, because 21244020555 - 2⁸ = 21244020299 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4655475 + ... + 4660035.

It is an arithmetic number, because the mean of its divisors is an integer number (570706200).

Almost surely, 2^21244020555 is an apocalyptic number.

21244020555 is a deficient number, since it is larger than the sum of its proper divisors (15281176245).

21244020555 is a wasteful number, since it uses less digits than its factorization.

21244020555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4924.

The product of its (nonzero) digits is 16000, while the sum is 30.

Adding to 21244020555 its reverse (55502044212), we get a palindrome (76746064767).

The spelling of 21244020555 in words is "twenty-one billion, two hundred forty-four million, twenty thousand, five hundred fifty-five".