81669601 has 4 divisors (see below), whose sum is σ = 87951892. Its totient is φ = 75387312.

The previous prime is 81669557. The next prime is 81669607. The reversal of 81669601 is 10696618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 10696618 = 2 ⋅5348309.

It can be written as a sum of positive squares in 2 ways, for example, as 33005025 + 48664576 = 5745^2 + 6976^2 .

It is not a de Polignac number, because 81669601 - 2⁷ = 81669473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81669607) 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, 3141126 + ... + 3141151.

It is an arithmetic number, because the mean of its divisors is an integer number (21987973).

Almost surely, 2^81669601 is an apocalyptic number.

It is an amenable number.

81669601 is a deficient number, since it is larger than the sum of its proper divisors (6282291).

81669601 is a wasteful number, since it uses less digits than its factorization.

81669601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6282290.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 81669601 is about 9037.1234914656. The cubic root of 81669601 is about 433.8638621757.

The spelling of 81669601 in words is "eighty-one million, six hundred sixty-nine thousand, six hundred one".