2491539128521 has 9 divisors (see below), whose sum is σ = 2495588133549. Its totient is φ = 2487496689900.

The previous prime is 2491539128513. The next prime is 2491539128641. The reversal of 2491539128521 is 1258219351942.

The square root of 2491539128521 is 1578461.

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

It is not a de Polignac number, because 2491539128521 - 2³ = 2491539128513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2491539128501) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1627392526 + ... + 1627394056.

Almost surely, 2^{2491539128521} is an apocalyptic number.

2491539128521 is the 1578461-st square number.

2491539128521 is the 789231-st centered octagonal number.

It is an amenable number.

2491539128521 is a deficient number, since it is larger than the sum of its proper divisors (4049005028).

2491539128521 is an frugal number, since it uses more digits than its factorization.

2491539128521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5124 (or 2562 counting only the distinct ones).

The product of its digits is 1555200, while the sum is 52.

The spelling of 2491539128521 in words is "two trillion, four hundred ninety-one billion, five hundred thirty-nine million, one hundred twenty-eight thousand, five hundred twenty-one".