21456563455 has 4 divisors (see below), whose sum is σ = 25747876152. Its totient is φ = 17165250760.

The previous prime is 21456563441. The next prime is 21456563461. The reversal of 21456563455 is 55436565412.

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

It is not a de Polignac number, because 21456563455 - 2⁷ = 21456563327 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2145656341 + ... + 2145656350.

It is an arithmetic number, because the mean of its divisors is an integer number (6436969038).

Almost surely, 2^21456563455 is an apocalyptic number.

21456563455 is a deficient number, since it is larger than the sum of its proper divisors (4291312697).

21456563455 is an equidigital number, since it uses as much as digits as its factorization.

21456563455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4291312696.

The product of its digits is 2160000, while the sum is 46.

The spelling of 21456563455 in words is "twenty-one billion, four hundred fifty-six million, five hundred sixty-three thousand, four hundred fifty-five".