21427021361 has 4 divisors (see below), whose sum is σ = 21667774500. Its totient is φ = 21186268224.

The previous prime is 21427021331. The next prime is 21427021381. The reversal of 21427021361 is 16312072412.

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 10641160336 + 10785861025 = 103156^2 + 103855^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21427021361 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21427021331) 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, 120376436 + ... + 120376613.

It is an arithmetic number, because the mean of its divisors is an integer number (5416943625).

Almost surely, 2^21427021361 is an apocalyptic number.

It is an amenable number.

21427021361 is a deficient number, since it is larger than the sum of its proper divisors (240753139).

21427021361 is an equidigital number, since it uses as much as digits as its factorization.

21427021361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240753138.

The product of its (nonzero) digits is 4032, while the sum is 29.

Adding to 21427021361 its reverse (16312072412), we get a palindrome (37739093773).

The spelling of 21427021361 in words is "twenty-one billion, four hundred twenty-seven million, twenty-one thousand, three hundred sixty-one".