81491392 has 84 divisors (see below), whose sum is σ = 176982120. Its totient is φ = 37176832.

The previous prime is 81491381. The next prime is 81491413. The reversal of 81491392 is 29319418.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 981783 + ... + 981865.

It is an arithmetic number, because the mean of its divisors is an integer number (2106930).

Almost surely, 2^81491392 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 81491392, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88491060).

81491392 is an abundant number, since it is smaller than the sum of its proper divisors (95490728).

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

81491392 is a wasteful number, since it uses less digits than its factorization.

81491392 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170 (or 137 counting only the distinct ones).

The product of its digits is 15552, while the sum is 37.

The square root of 81491392 is about 9027.2582770186. The cubic root of 81491392 is about 433.5480582107.

The spelling of 81491392 in words is "eighty-one million, four hundred ninety-one thousand, three hundred ninety-two".