21638098945 has 32 divisors (see below), whose sum is σ = 26991641376. Its totient is φ = 16638566400.

The previous prime is 21638098943. The next prime is 21638098957. The reversal of 21638098945 is 54989083612.

It can be written as a sum of positive squares in 16 ways, for example, as 14984641 + 21623114304 = 3871^2 + 147048^2 .

It is not a de Polignac number, because 21638098945 - 2¹ = 21638098943 is a prime.

It is a super-2 number, since 2×21638098945² (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 (21638098943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18321255 + ... + 18322435.

It is an arithmetic number, because the mean of its divisors is an integer number (843488793).

Almost surely, 2^21638098945 is an apocalyptic number.

It is an amenable number.

21638098945 is a deficient number, since it is larger than the sum of its proper divisors (5353542431).

21638098945 is a wasteful number, since it uses less digits than its factorization.

21638098945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2341.

The product of its (nonzero) digits is 3732480, while the sum is 55.

The spelling of 21638098945 in words is "twenty-one billion, six hundred thirty-eight million, ninety-eight thousand, nine hundred forty-five".