21489871489 has 4 divisors (see below), whose sum is σ = 21573489924. Its totient is φ = 21406253056.

The previous prime is 21489871471. The next prime is 21489871541. The reversal of 21489871489 is 98417898412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19261276225 + 2228595264 = 138785^2 + 47208^2 .

It is a cyclic number.

It is not a de Polignac number, because 21489871489 - 2⁹ = 21489870977 is a prime.

It is a super-2 number, since 2×21489871489² (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 (21489871439) 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 3 ways as a sum of consecutive naturals, for example, 41808832 + ... + 41809345.

It is an arithmetic number, because the mean of its divisors is an integer number (5393372481).

Almost surely, 2^21489871489 is an apocalyptic number.

It is an amenable number.

21489871489 is a deficient number, since it is larger than the sum of its proper divisors (83618435).

21489871489 is an equidigital number, since it uses as much as digits as its factorization.

21489871489 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83618434.

The product of its digits is 9289728, while the sum is 61.

The spelling of 21489871489 in words is "twenty-one billion, four hundred eighty-nine million, eight hundred seventy-one thousand, four hundred eighty-nine".