21260451505 has 4 divisors (see below), whose sum is σ = 25512541812. Its totient is φ = 17008361200.

The previous prime is 21260451503. The next prime is 21260451517. The reversal of 21260451505 is 50515406212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6500874384 + 14759577121 = 80628^2 + 121489^2 .

It is not a de Polignac number, because 21260451505 - 2¹ = 21260451503 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21260451503) 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, 2126045146 + ... + 2126045155.

It is an arithmetic number, because the mean of its divisors is an integer number (6378135453).

Almost surely, 2^21260451505 is an apocalyptic number.

It is an amenable number.

21260451505 is a deficient number, since it is larger than the sum of its proper divisors (4252090307).

21260451505 is an equidigital number, since it uses as much as digits as its factorization.

21260451505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4252090306.

The product of its (nonzero) digits is 12000, while the sum is 31.

Adding to 21260451505 its reverse (50515406212), we get a palindrome (71775857717).

The spelling of 21260451505 in words is "twenty-one billion, two hundred sixty million, four hundred fifty-one thousand, five hundred five".