21455443540225 has 12 divisors (see below), whose sum is σ = 26607066017580. Its totient is φ = 17162860620800.

The previous prime is 21455443540087. The next prime is 21455443540229. The reversal of 21455443540225 is 52204534455412.

It can be written as a sum of positive squares in 6 ways, for example, as 1555288340544 + 19900155199681 = 1247112^2 + 4460959^2 .

It is not a de Polignac number, because 21455443540225 - 2³³ = 21446853605633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21455443540229) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 37062316 + ... + 37636765.

It is an arithmetic number, because the mean of its divisors is an integer number (2217255501465).

Almost surely, 2^{21455443540225} is an apocalyptic number.

21455443540225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21455443540225 is a deficient number, since it is larger than the sum of its proper divisors (5151622477355).

21455443540225 is a wasteful number, since it uses less digits than its factorization.

21455443540225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74710580 (or 74710575 counting only the distinct ones).

The product of its (nonzero) digits is 3840000, while the sum is 46.

Adding to 21455443540225 its reverse (52204534455412), we get a palindrome (73659977995637).

The spelling of 21455443540225 in words is "twenty-one trillion, four hundred fifty-five billion, four hundred forty-three million, five hundred forty thousand, two hundred twenty-five".