81281694 has 32 divisors (see below), whose sum is σ = 176722560. Its totient is φ = 24773472.

The previous prime is 81281687. The next prime is 81281713. The reversal of 81281694 is 49618218.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3477 + ... + 13215.

It is an arithmetic number, because the mean of its divisors is an integer number (5522580).

Almost surely, 2^81281694 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81281694, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88361280).

81281694 is an abundant number, since it is smaller than the sum of its proper divisors (95440866).

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

81281694 is a wasteful number, since it uses less digits than its factorization.

81281694 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9864.

The product of its digits is 27648, while the sum is 39.

The square root of 81281694 is about 9015.6360840486. The cubic root of 81281694 is about 433.1758624410.

The spelling of 81281694 in words is "eighty-one million, two hundred eighty-one thousand, six hundred ninety-four".