81656663 has 8 divisors (see below), whose sum is σ = 92152080. Its totient is φ = 71673280.

The previous prime is 81656657. The next prime is 81656671. The reversal of 81656663 is 36665618.

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 81656663 - 2⁶ = 81656599 is a prime.

It is a super-2 number, since 2×81656663² = 13335621224591138, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81656663.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81656063) 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 7 ways as a sum of consecutive naturals, for example, 127670 + ... + 128307.

It is an arithmetic number, because the mean of its divisors is an integer number (11519010).

Almost surely, 2^81656663 is an apocalyptic number.

81656663 is a deficient number, since it is larger than the sum of its proper divisors (10495417).

81656663 is a wasteful number, since it uses less digits than its factorization.

81656663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 256017.

The product of its digits is 155520, while the sum is 41.

The square root of 81656663 is about 9036.4076379942. The cubic root of 81656663 is about 433.8409502353.

The spelling of 81656663 in words is "eighty-one million, six hundred fifty-six thousand, six hundred sixty-three".