21678638255 has 16 divisors (see below), whose sum is σ = 27955743840. Its totient is φ = 16079112192.

The previous prime is 21678638251. The next prime is 21678638287. The reversal of 21678638255 is 55283687612.

It is a cyclic number.

It is not a de Polignac number, because 21678638255 - 2² = 21678638251 is a prime.

It is a super-2 number, since 2×21678638255² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21678638197 and 21678638206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21678638251) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1897610 + ... + 1908999.

It is an arithmetic number, because the mean of its divisors is an integer number (1747233990).

Almost surely, 2^21678638255 is an apocalyptic number.

21678638255 is a deficient number, since it is larger than the sum of its proper divisors (6277105585).

21678638255 is a wasteful number, since it uses less digits than its factorization.

21678638255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3806698.

The product of its digits is 4838400, while the sum is 53.

The spelling of 21678638255 in words is "twenty-one billion, six hundred seventy-eight million, six hundred thirty-eight thousand, two hundred fifty-five".