21255240371 has 16 divisors (see below), whose sum is σ = 21615759360. Its totient is φ = 20898151680.

The previous prime is 21255240341. The next prime is 21255240389. The reversal of 21255240371 is 17304255212.

It is a cyclic number.

It is not a de Polignac number, because 21255240371 - 2¹⁴ = 21255223987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21255240311) 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, 18275636 + ... + 18276798.

It is an arithmetic number, because the mean of its divisors is an integer number (1350984960).

Almost surely, 2^21255240371 is an apocalyptic number.

21255240371 is a deficient number, since it is larger than the sum of its proper divisors (360518989).

21255240371 is a wasteful number, since it uses less digits than its factorization.

21255240371 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2386.

The product of its (nonzero) digits is 16800, while the sum is 32.

Adding to 21255240371 its reverse (17304255212), we get a palindrome (38559495583).

The spelling of 21255240371 in words is "twenty-one billion, two hundred fifty-five million, two hundred forty thousand, three hundred seventy-one".