21285946369 has 4 divisors (see below), whose sum is σ = 21377302596. Its totient is φ = 21194590144.

The previous prime is 21285946351. The next prime is 21285946433. The reversal of 21285946369 is 96364958212.

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 1891206144 + 19394740225 = 43488^2 + 139265^2 .

It is a cyclic number.

It is not a de Polignac number, because 21285946369 - 2¹⁷ = 21285815297 is a prime.

It is a super-2 number, since 2×21285946369² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21285946349) 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, 45677764 + ... + 45678229.

It is an arithmetic number, because the mean of its divisors is an integer number (5344325649).

Almost surely, 2^21285946369 is an apocalyptic number.

It is an amenable number.

21285946369 is a deficient number, since it is larger than the sum of its proper divisors (91356227).

21285946369 is an equidigital number, since it uses as much as digits as its factorization.

21285946369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91356226.

The product of its digits is 5598720, while the sum is 55.

The spelling of 21285946369 in words is "twenty-one billion, two hundred eighty-five million, nine hundred forty-six thousand, three hundred sixty-nine".