81663708 has 96 divisors (see below), whose sum is σ = 232759296. Its totient is φ = 21776832.

The previous prime is 81663683. The next prime is 81663709. The reversal of 81663708 is 80736618.

It is a super-2 number, since 2×81663708² = 13337922408618528, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81663709) 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, 82585 + ... + 83567.

It is an arithmetic number, because the mean of its divisors is an integer number (2424576).

Almost surely, 2^81663708 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81663708, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (116379648).

81663708 is an abundant number, since it is smaller than the sum of its proper divisors (151095588).

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

81663708 is a wasteful number, since it uses less digits than its factorization.

81663708 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1063 (or 1061 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 39.

The square root of 81663708 is about 9036.7974415719. The cubic root of 81663708 is about 433.8534265456.

The spelling of 81663708 in words is "eighty-one million, six hundred sixty-three thousand, seven hundred eight".