12987109521 has 9 divisors (see below), whose sum is σ = 18759652041. Its totient is φ = 8657845092.

The previous prime is 12987109507. The next prime is 12987109547. The reversal of 12987109521 is 12590178921.

The square root of 12987109521 is 113961.

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

12987109521 is a `hidden beast` number, since 12 + 9 + 8 + 7 + 109 + 521 = 666.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 12987109521 - 2¹⁹ = 12986585233 is a prime.

It is not an unprimeable number, because it can be changed into a prime (12987109561) 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 8 ways as a sum of consecutive naturals, for example, 322890 + ... + 360876.

Almost surely, 2^12987109521 is an apocalyptic number.

12987109521 is the 113961-st square number.

12987109521 is the 56981-st centered octagonal number.

It is an amenable number.

12987109521 is a deficient number, since it is larger than the sum of its proper divisors (5772542520).

12987109521 is an frugal number, since it uses more digits than its factorization.

12987109521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75980 (or 37990 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 45.

The spelling of 12987109521 in words is "twelve billion, nine hundred eighty-seven million, one hundred nine thousand, five hundred twenty-one".