1581152838721 has 45 divisors (see below), whose sum is σ = 1780823417391. Its totient is φ = 1403664066432.

The previous prime is 1581152838659. The next prime is 1581152838739. The reversal of 1581152838721 is 1278382511851.

The square root of 1581152838721 is 1257439.

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

It can be written as a sum of positive squares in 7 ways, for example, as 161957148721 + 1419195690000 = 402439^2 + 1191300^2 .

It is not a de Polignac number, because 1581152838721 - 2¹³ = 1581152830529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1581152838761) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 6904597435 + ... + 6904597663.

Almost surely, 2^{1581152838721} is an apocalyptic number.

1581152838721 is the 1257439-th square number.

1581152838721 is the 628720-th centered octagonal number.

It is an amenable number.

1581152838721 is a deficient number, since it is larger than the sum of its proper divisors (199670578670).

1581152838721 is an frugal number, since it uses more digits than its factorization.

1581152838721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 564 (or 265 counting only the distinct ones).

The product of its digits is 1075200, while the sum is 52.

The spelling of 1581152838721 in words is "one trillion, five hundred eighty-one billion, one hundred fifty-two million, eight hundred thirty-eight thousand, seven hundred twenty-one".