20421021265 has 8 divisors (see below), whose sum is σ = 25946709480. Its totient is φ = 15375827712.

The previous prime is 20421021259. The next prime is 20421021281. The reversal of 20421021265 is 56212012402.

It can be written as a sum of positive squares in 4 ways, for example, as 8712915649 + 11708105616 = 93343^2 + 108204^2 .

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 20421021265 - 2¹¹ = 20421019217 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 120123570 + ... + 120123739.

It is an arithmetic number, because the mean of its divisors is an integer number (3243338685).

Almost surely, 2^20421021265 is an apocalyptic number.

It is an amenable number.

20421021265 is a deficient number, since it is larger than the sum of its proper divisors (5525688215).

20421021265 is a wasteful number, since it uses less digits than its factorization.

20421021265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240247331.

The product of its (nonzero) digits is 1920, while the sum is 25.

Adding to 20421021265 its reverse (56212012402), we get a palindrome (76633033667).

The spelling of 20421021265 in words is "twenty billion, four hundred twenty-one million, twenty-one thousand, two hundred sixty-five".