21538945389 has 24 divisors (see below), whose sum is σ = 31624771680. Its totient is φ = 13030060992.

The previous prime is 21538945369. The next prime is 21538945391. The reversal of 21538945389 is 98354983512.

It is a happy number.

It is not a de Polignac number, because 21538945389 - 2¹⁵ = 21538912621 is a prime.

It is a super-2 number, since 2×21538945389² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21538945339) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 330114 + ... + 389939.

It is an arithmetic number, because the mean of its divisors is an integer number (1317698820).

Almost surely, 2^21538945389 is an apocalyptic number.

It is an amenable number.

21538945389 is a deficient number, since it is larger than the sum of its proper divisors (10085826291).

21538945389 is a wasteful number, since it uses less digits than its factorization.

21538945389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 720141 (or 720128 counting only the distinct ones).

The product of its digits is 9331200, while the sum is 57.

The spelling of 21538945389 in words is "twenty-one billion, five hundred thirty-eight million, nine hundred forty-five thousand, three hundred eighty-nine".