21678112225 has 192 divisors, whose sum is σ = 36857640960. Its totient is φ = 12242534400.

The previous prime is 21678112223. The next prime is 21678112259. The reversal of 21678112225 is 52221187612.

It is a happy number.

It is not a de Polignac number, because 21678112225 - 2¹ = 21678112223 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is not an unprimeable number, because it can be changed into a prime (21678112223) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 112321729 + ... + 112321921.

It is an arithmetic number, because the mean of its divisors is an integer number (191966880).

Almost surely, 2^21678112225 is an apocalyptic number.

21678112225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21678112225 is a deficient number, since it is larger than the sum of its proper divisors (15179528735).

21678112225 is a wasteful number, since it uses less digits than its factorization.

21678112225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 360 (or 355 counting only the distinct ones).

The product of its digits is 26880, while the sum is 37.

Adding to 21678112225 its reverse (52221187612), we get a palindrome (73899299837).

It can be divided in two parts, 21678 and 112225, that added together give a triangular number (133903 = T₅₁₇).

The spelling of 21678112225 in words is "twenty-one billion, six hundred seventy-eight million, one hundred twelve thousand, two hundred twenty-five".