21189751489 has 9 divisors (see below), whose sum is σ = 22154601763. Its totient is φ = 20265255472.

The previous prime is 21189751441. The next prime is 21189751543. The reversal of 21189751489 is 98415798112.

The square root of 21189751489 is 145567.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 16171445889 + 5018305600 = 127167^2 + 70840^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21189751489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21189751409) 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 8 ways as a sum of consecutive naturals, for example, 3344877 + ... + 3351205.

Almost surely, 2^21189751489 is an apocalyptic number.

21189751489 is the 145567-th square number.

21189751489 is the 72784-th centered octagonal number.

It is an amenable number.

21189751489 is a deficient number, since it is larger than the sum of its proper divisors (964850274).

21189751489 is an frugal number, since it uses more digits than its factorization.

21189751489 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12704 (or 6352 counting only the distinct ones).

The product of its digits is 1451520, while the sum is 55.

The spelling of 21189751489 in words is "twenty-one billion, one hundred eighty-nine million, seven hundred fifty-one thousand, four hundred eighty-nine".