81669579 has 4 divisors (see below), whose sum is σ = 108892776. Its totient is φ = 54446384.

The previous prime is 81669557. The next prime is 81669607. The reversal of 81669579 is 97596618.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81669579 - 2⁷ = 81669451 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81669079) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13611594 + ... + 13611599.

It is an arithmetic number, because the mean of its divisors is an integer number (27223194).

Almost surely, 2^81669579 is an apocalyptic number.

81669579 is a deficient number, since it is larger than the sum of its proper divisors (27223197).

81669579 is a wasteful number, since it uses less digits than its factorization.

81669579 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27223196.

The product of its digits is 816480, while the sum is 51.

The square root of 81669579 is about 9037.1222742641. The cubic root of 81669579 is about 433.8638232179.

The spelling of 81669579 in words is "eighty-one million, six hundred sixty-nine thousand, five hundred seventy-nine".