20404241521 has 2 divisors, whose sum is σ = 20404241522. Its totient is φ = 20404241520.

The previous prime is 20404241497. The next prime is 20404241537. The reversal of 20404241521 is 12514240402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20345028496 + 59213025 = 142636^2 + 7695^2 .

It is a cyclic number.

It is not a de Polignac number, because 20404241521 - 2²³ = 20395852913 is a prime.

It is not a weakly prime, because it can be changed into another prime (20404241021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10202120760 + 10202120761.

It is an arithmetic number, because the mean of its divisors is an integer number (10202120761).

Almost surely, 2^20404241521 is an apocalyptic number.

It is an amenable number.

20404241521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20404241521 is an equidigital number, since it uses as much as digits as its factorization.

20404241521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2560, while the sum is 25.

Adding to 20404241521 its reverse (12514240402), we get a palindrome (32918481923).

The spelling of 20404241521 in words is "twenty billion, four hundred four million, two hundred forty-one thousand, five hundred twenty-one".