81751790 has 16 divisors (see below), whose sum is σ = 147705120. Its totient is φ = 32578080.

The previous prime is 81751777. The next prime is 81751799. The reversal of 81751790 is 9715718.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81751799) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12506 + ... + 17885.

It is an arithmetic number, because the mean of its divisors is an integer number (9231570).

Almost surely, 2^81751790 is an apocalyptic number.

81751790 is a deficient number, since it is larger than the sum of its proper divisors (65953330).

81751790 is a wasteful number, since it uses less digits than its factorization.

81751790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30667.

The product of its (nonzero) digits is 17640, while the sum is 38.

The square root of 81751790 is about 9041.6696466969. The cubic root of 81751790 is about 434.0093544247.

The spelling of 81751790 in words is "eighty-one million, seven hundred fifty-one thousand, seven hundred ninety".