81668757 has 8 divisors (see below), whose sum is σ = 108941760. Its totient is φ = 54420800.

The previous prime is 81668753. The next prime is 81668767. The reversal of 81668757 is 75786618.

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 81668757 - 2² = 81668753 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81668753) 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, 3544 + ... + 13262.

It is an arithmetic number, because the mean of its divisors is an integer number (13617720).

Almost surely, 2^81668757 is an apocalyptic number.

It is an amenable number.

81668757 is a deficient number, since it is larger than the sum of its proper divisors (27273003).

81668757 is a wasteful number, since it uses less digits than its factorization.

81668757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12523.

The product of its digits is 564480, while the sum is 48.

The square root of 81668757 is about 9037.0767950704. The cubic root of 81668757 is about 433.8623676075.

The spelling of 81668757 in words is "eighty-one million, six hundred sixty-eight thousand, seven hundred fifty-seven".