81669717 has 48 divisors (see below), whose sum is σ = 131369472. Its totient is φ = 48660480.

The previous prime is 81669703. The next prime is 81669719. The reversal of 81669717 is 71796618.

It is not a de Polignac number, because 81669717 - 2⁴ = 81669701 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

Its product of digits (127008) is a multiple of the sum of its prime factors (378).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81669719) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 317653 + ... + 317909.

It is an arithmetic number, because the mean of its divisors is an integer number (2736864).

Almost surely, 2^81669717 is an apocalyptic number.

It is an amenable number.

81669717 is a deficient number, since it is larger than the sum of its proper divisors (49699755).

81669717 is a wasteful number, since it uses less digits than its factorization.

81669717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 378 (or 375 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The square root of 81669717 is about 9037.1299094347. The cubic root of 81669717 is about 433.8640675895.

The spelling of 81669717 in words is "eighty-one million, six hundred sixty-nine thousand, seven hundred seventeen".