20266431521 has 4 divisors (see below), whose sum is σ = 23161636032. Its totient is φ = 17371227012.

The previous prime is 20266431517. The next prime is 20266431547. The reversal of 20266431521 is 12513466202.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20266431521 - 2² = 20266431517 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20266431571) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1447602245 + ... + 1447602258.

It is an arithmetic number, because the mean of its divisors is an integer number (5790409008).

Almost surely, 2^20266431521 is an apocalyptic number.

It is an amenable number.

20266431521 is a deficient number, since it is larger than the sum of its proper divisors (2895204511).

20266431521 is an equidigital number, since it uses as much as digits as its factorization.

20266431521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2895204510.

The product of its (nonzero) digits is 17280, while the sum is 32.

Adding to 20266431521 its reverse (12513466202), we get a palindrome (32779897723).

The spelling of 20266431521 in words is "twenty billion, two hundred sixty-six million, four hundred thirty-one thousand, five hundred twenty-one".