21405463673255 has 4 divisors (see below), whose sum is σ = 25686556407912. Its totient is φ = 17124370938600.

The previous prime is 21405463673233. The next prime is 21405463673257. The reversal of 21405463673255 is 55237636450412.

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

It is a de Polignac number, because none of the positive numbers 2^k-21405463673255 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21405463673197 and 21405463673206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21405463673257) 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, 2140546367321 + ... + 2140546367330.

It is an arithmetic number, because the mean of its divisors is an integer number (6421639101978).

Almost surely, 2^{21405463673255} is an apocalyptic number.

21405463673255 is a deficient number, since it is larger than the sum of its proper divisors (4281092734657).

21405463673255 is an equidigital number, since it uses as much as digits as its factorization.

21405463673255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4281092734656.

The product of its (nonzero) digits is 18144000, while the sum is 53.

The spelling of 21405463673255 in words is "twenty-one trillion, four hundred five billion, four hundred sixty-three million, six hundred seventy-three thousand, two hundred fifty-five".