81663671 has 8 divisors (see below), whose sum is σ = 82296000. Its totient is φ = 81034240.

The previous prime is 81663649. The next prime is 81663683. The reversal of 81663671 is 17636618.

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

It is a cyclic number.

It is not a de Polignac number, because 81663671 - 2⁶ = 81663607 is a prime.

It is a super-2 number, since 2×81663671² = 13337910322392482, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81663871) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 106931 + ... + 107691.

It is an arithmetic number, because the mean of its divisors is an integer number (10287000).

Almost surely, 2^81663671 is an apocalyptic number.

81663671 is a deficient number, since it is larger than the sum of its proper divisors (632329).

81663671 is a wasteful number, since it uses less digits than its factorization.

81663671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1449.

The product of its digits is 36288, while the sum is 38.

The square root of 81663671 is about 9036.7953943862. The cubic root of 81663671 is about 433.8533610225.

The spelling of 81663671 in words is "eighty-one million, six hundred sixty-three thousand, six hundred seventy-one".