81909782 has 8 divisors (see below), whose sum is σ = 123618936. Its totient is φ = 40703472.

The previous prime is 81909761. The next prime is 81909787. The reversal of 81909782 is 28790918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81909787) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 125303 + ... + 125954.

It is an arithmetic number, because the mean of its divisors is an integer number (15452367).

Almost surely, 2^81909782 is an apocalyptic number.

81909782 is a deficient number, since it is larger than the sum of its proper divisors (41709154).

81909782 is a wasteful number, since it uses less digits than its factorization.

81909782 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251422.

The product of its (nonzero) digits is 72576, while the sum is 44.

The square root of 81909782 is about 9050.4023114997. The cubic root of 81909782 is about 434.2887606653.

The spelling of 81909782 in words is "eighty-one million, nine hundred nine thousand, seven hundred eighty-two".