81785836 has 36 divisors (see below), whose sum is σ = 161606704. Its totient is φ = 36162720.

The previous prime is 81785833. The next prime is 81785839. The reversal of 81785836 is 63858718.

It is an interprime number because it is at equal distance from previous prime (81785833) and next prime (81785839).

It is not an unprimeable number, because it can be changed into a prime (81785833) 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 11 ways as a sum of consecutive naturals, for example, 15625 + ... + 20191.

Almost surely, 2^81785836 is an apocalyptic number.

It is an amenable number.

81785836 is a deficient number, since it is larger than the sum of its proper divisors (79820868).

81785836 is a wasteful number, since it uses less digits than its factorization.

81785836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4630 (or 4617 counting only the distinct ones).

The product of its digits is 322560, while the sum is 46.

The square root of 81785836 is about 9043.5521782096. The cubic root of 81785836 is about 434.0695946214.

It can be divided in two parts, 81785 and 836, that added together give a triangular number (82621 = T₄₀₆).

The spelling of 81785836 in words is "eighty-one million, seven hundred eighty-five thousand, eight hundred thirty-six".