81906760 has 32 divisors (see below), whose sum is σ = 198467640. Its totient is φ = 30242304.

The previous prime is 81906719. The next prime is 81906823. The reversal of 81906760 is 6760918.

It can be written as a sum of positive squares in 4 ways, for example, as 63776196 + 18130564 = 7986^2 + 4258^2 .

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 78237 + ... + 79276.

Almost surely, 2^81906760 is an apocalyptic number.

It is an amenable number.

81906760 is an abundant number, since it is smaller than the sum of its proper divisors (116560880).

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

81906760 is a wasteful number, since it uses less digits than its factorization.

81906760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157537 (or 157533 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 37.

The square root of 81906760 is about 9050.2353560557. The cubic root of 81906760 is about 434.2834196802.

The spelling of 81906760 in words is "eighty-one million, nine hundred six thousand, seven hundred sixty".