81663835 has 32 divisors (see below), whose sum is σ = 114089472. Its totient is φ = 55457280.

The previous prime is 81663833. The next prime is 81663851. The reversal of 81663835 is 53836618.

It is not a de Polignac number, because 81663835 - 2¹ = 81663833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81663833) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 155884 + ... + 156406.

It is an arithmetic number, because the mean of its divisors is an integer number (3565296).

Almost surely, 2^81663835 is an apocalyptic number.

81663835 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

81663835 is a deficient number, since it is larger than the sum of its proper divisors (32425637).

81663835 is a wasteful number, since it uses less digits than its factorization.

81663835 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 723.

The product of its digits is 103680, while the sum is 40.

The square root of 81663835 is about 9036.8044683948. The cubic root of 81663835 is about 433.8536514491.

The spelling of 81663835 in words is "eighty-one million, six hundred sixty-three thousand, eight hundred thirty-five".