81073251584 has 72 divisors (see below), whose sum is σ = 174374371752. Its totient is φ = 37397790720.

The previous prime is 81073251569. The next prime is 81073251587. The reversal of 81073251584 is 48515237018.

It can be written as a sum of positive squares in 4 ways, for example, as 1395769600 + 79677481984 = 37360^2 + 282272^2 .

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81073251587) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7186172 + ... + 7197444.

Almost surely, 2^81073251584 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81073251584, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87187185876).

81073251584 is an abundant number, since it is smaller than the sum of its proper divisors (93301120168).

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

81073251584 is a wasteful number, since it uses less digits than its factorization.

81073251584 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13463 (or 13449 counting only the distinct ones).

The product of its (nonzero) digits is 268800, while the sum is 44.

The spelling of 81073251584 in words is "eighty-one billion, seventy-three million, two hundred fifty-one thousand, five hundred eighty-four".