81669599 has 8 divisors (see below), whose sum is σ = 91166592. Its totient is φ = 72518040.

The previous prime is 81669557. The next prime is 81669607. The reversal of 81669599 is 99596618.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81669599 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81669599.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81669899) 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, 85859 + ... + 86804.

It is an arithmetic number, because the mean of its divisors is an integer number (11395824).

Almost surely, 2^81669599 is an apocalyptic number.

81669599 is a deficient number, since it is larger than the sum of its proper divisors (9496993).

81669599 is a wasteful number, since it uses less digits than its factorization.

81669599 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172717.

The product of its digits is 1049760, while the sum is 53.

The square root of 81669599 is about 9037.1233808110. The cubic root of 81669599 is about 433.8638586341.

The spelling of 81669599 in words is "eighty-one million, six hundred sixty-nine thousand, five hundred ninety-nine".