81361457320 has 128 divisors (see below), whose sum is σ = 215486490240. Its totient is φ = 27256919040.

The previous prime is 81361457311. The next prime is 81361457321. The reversal of 81361457320 is 2375416318.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is not an unprimeable number, because it can be changed into a prime (81361457321) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2977962 + ... + 3005158.

It is an arithmetic number, because the mean of its divisors is an integer number (1683488205).

Almost surely, 2^81361457320 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 81361457320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (107743245120).

81361457320 is an abundant number, since it is smaller than the sum of its proper divisors (134125032920).

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

81361457320 is a wasteful number, since it uses less digits than its factorization.

81361457320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27755 (or 27751 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 40.

The spelling of 81361457320 in words is "eighty-one billion, three hundred sixty-one million, four hundred fifty-seven thousand, three hundred twenty".