81511794 has 72 divisors (see below), whose sum is σ = 221277420. Its totient is φ = 21494592.

The previous prime is 81511757. The next prime is 81511819. The reversal of 81511794 is 49711518.

It can be written as a sum of positive squares in 2 ways, for example, as 69505569 + 12006225 = 8337^2 + 3465^2 .

It is a super-2 number, since 2×81511794² = 13288345122196872, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 7912 + ... + 15020.

Almost surely, 2^81511794 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81511794, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (110638710).

81511794 is an abundant number, since it is smaller than the sum of its proper divisors (139765626).

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

81511794 is a wasteful number, since it uses less digits than its factorization.

81511794 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7144 (or 7134 counting only the distinct ones).

The product of its digits is 10080, while the sum is 36.

The square root of 81511794 is about 9028.3882282498. The cubic root of 81511794 is about 433.5842358945.

The spelling of 81511794 in words is "eighty-one million, five hundred eleven thousand, seven hundred ninety-four".