20355440521 has 8 divisors (see below), whose sum is σ = 21927168200. Its totient is φ = 18784559232.

The previous prime is 20355440507. The next prime is 20355440527. The reversal of 20355440521 is 12504455302.

It can be written as a sum of positive squares in 4 ways, for example, as 168714121 + 20186726400 = 12989^2 + 142080^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20355440521 - 2¹⁷ = 20355309449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20355440527) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161196 + ... + 258253.

It is an arithmetic number, because the mean of its divisors is an integer number (2740896025).

Almost surely, 2^20355440521 is an apocalyptic number.

It is an amenable number.

20355440521 is a deficient number, since it is larger than the sum of its proper divisors (1571727679).

20355440521 is a wasteful number, since it uses less digits than its factorization.

20355440521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423195.

The product of its (nonzero) digits is 24000, while the sum is 31.

Adding to 20355440521 its reverse (12504455302), we get a palindrome (32859895823).

The spelling of 20355440521 in words is "twenty billion, three hundred fifty-five million, four hundred forty thousand, five hundred twenty-one".