8261991399424 has 189 divisors, whose sum is σ = 19269820861221. Its totient is φ = 3532023398400.

The previous prime is 8261991399401. The next prime is 8261991399433. The reversal of 8261991399424 is 4249931991628.

The square root of 8261991399424 is 2874368.

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., 8179783041024 + 82208358400 = 2860032^2 + 286720^2 .

It is a super-2 number, since 2×8261991399424² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 8261991399424.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 20603469624 + ... + 20603470024.

Almost surely, 2^{8261991399424} is an apocalyptic number.

8261991399424 is the 2874368-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 8261991399424

8261991399424 is an abundant number, since it is smaller than the sum of its proper divisors (11007829461797).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

8261991399424 is an frugal number, since it uses more digits than its factorization.

8261991399424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 856 (or 410 counting only the distinct ones).

The product of its digits is 60466176, while the sum is 67.

The spelling of 8261991399424 in words is "eight trillion, two hundred sixty-one billion, nine hundred ninety-one million, three hundred ninety-nine thousand, four hundred twenty-four".