21450344555 has 4 divisors (see below), whose sum is σ = 25740413472. Its totient is φ = 17160275640.

The previous prime is 21450344551. The next prime is 21450344623. The reversal of 21450344555 is 55544305412.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21450344555 - 2² = 21450344551 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21450344551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2145034451 + ... + 2145034460.

It is an arithmetic number, because the mean of its divisors is an integer number (6435103368).

Almost surely, 2^21450344555 is an apocalyptic number.

21450344555 is a deficient number, since it is larger than the sum of its proper divisors (4290068917).

21450344555 is an equidigital number, since it uses as much as digits as its factorization.

21450344555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4290068916.

The product of its (nonzero) digits is 240000, while the sum is 38.

Adding to 21450344555 its reverse (55544305412), we get a palindrome (76994649967).

The spelling of 21450344555 in words is "twenty-one billion, four hundred fifty million, three hundred forty-four thousand, five hundred fifty-five".