21289782645 has 24 divisors (see below), whose sum is σ = 36908328600. Its totient is φ = 11352692736.

The previous prime is 21289782643. The next prime is 21289782659. The reversal of 21289782645 is 54628798212.

It can be written as a sum of positive squares in 4 ways, for example, as 6247005444 + 15042777201 = 79038^2 + 122649^2 .

It is not a de Polignac number, because 21289782645 - 2¹ = 21289782643 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21289782591 and 21289782600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21289782641) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 265641 + ... + 336369.

It is an arithmetic number, because the mean of its divisors is an integer number (1537847025).

Almost surely, 2^21289782645 is an apocalyptic number.

It is an amenable number.

21289782645 is a deficient number, since it is larger than the sum of its proper divisors (15618545955).

21289782645 is a wasteful number, since it uses less digits than its factorization.

21289782645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77429 (or 77426 counting only the distinct ones).

The product of its digits is 3870720, while the sum is 54.

The spelling of 21289782645 in words is "twenty-one billion, two hundred eighty-nine million, seven hundred eighty-two thousand, six hundred forty-five".