21005424045 has 24 divisors (see below), whose sum is σ = 36498454200. Its totient is φ = 11175492096.

The previous prime is 21005424007. The next prime is 21005424047. The reversal of 21005424045 is 54042450012.

21005424045 is a `hidden beast` number, since 210 + 0 + 5 + 42 + 404 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 11510285796 + 9495138249 = 107286^2 + 97443^2 .

It is not a de Polignac number, because 21005424045 - 2¹⁸ = 21005161901 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005424047) 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, 552240 + ... + 589049.

It is an arithmetic number, because the mean of its divisors is an integer number (1520768925).

Almost surely, 2^21005424045 is an apocalyptic number.

It is an amenable number.

21005424045 is a deficient number, since it is larger than the sum of its proper divisors (15493030155).

21005424045 is a wasteful number, since it uses less digits than its factorization.

21005424045 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1141709 (or 1141706 counting only the distinct ones).

The product of its (nonzero) digits is 6400, while the sum is 27.

Adding to 21005424045 its reverse (54042450012), we get a palindrome (75047874057).

The spelling of 21005424045 in words is "twenty-one billion, five million, four hundred twenty-four thousand, forty-five".