21334453561 has 6 divisors (see below), whose sum is σ = 21926645790. Its totient is φ = 20757845376.

The previous prime is 21334453477. The next prime is 21334453661. The reversal of 21334453561 is 16535443312.

It can be written as a sum of positive squares in 3 ways, for example, as 7204614400 + 14129839161 = 84880^2 + 118869^2 .

It is not a de Polignac number, because 21334453561 - 2²⁹ = 20797582649 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21334453561.

It is not an unprimeable number, because it can be changed into a prime (21334453661) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7790616 + ... + 7793353.

It is an arithmetic number, because the mean of its divisors is an integer number (3654440965).

Almost surely, 2^21334453561 is an apocalyptic number.

It is an amenable number.

21334453561 is a deficient number, since it is larger than the sum of its proper divisors (592192229).

21334453561 is an equidigital number, since it uses as much as digits as its factorization.

21334453561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15584043 (or 15584006 counting only the distinct ones).

The product of its digits is 129600, while the sum is 37.

Adding to 21334453561 its reverse (16535443312), we get a palindrome (37869896873).

The spelling of 21334453561 in words is "twenty-one billion, three hundred thirty-four million, four hundred fifty-three thousand, five hundred sixty-one".