21255440123361 has 16 divisors (see below), whose sum is σ = 28600985726720. Its totient is φ = 14040097545600.

The previous prime is 21255440123303. The next prime is 21255440123431. The reversal of 21255440123361 is 16332104455212.

It is not a de Polignac number, because 21255440123361 - 2¹⁰ = 21255440122337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21255440123161) 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, 25687656 + ... + 26502198.

It is an arithmetic number, because the mean of its divisors is an integer number (1787561607920).

Almost surely, 2^{21255440123361} is an apocalyptic number.

It is an amenable number.

21255440123361 is a deficient number, since it is larger than the sum of its proper divisors (7345545603359).

21255440123361 is a wasteful number, since it uses less digits than its factorization.

21255440123361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 894456.

The product of its (nonzero) digits is 172800, while the sum is 39.

Adding to 21255440123361 its reverse (16332104455212), we get a palindrome (37587544578573).

The spelling of 21255440123361 in words is "twenty-one trillion, two hundred fifty-five billion, four hundred forty million, one hundred twenty-three thousand, three hundred sixty-one".