81520067 has 4 divisors (see below), whose sum is σ = 81810456. Its totient is φ = 81229680.

The previous prime is 81520063. The next prime is 81520079. The reversal of 81520067 is 76002518.

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 81520067 - 2² = 81520063 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81520063) 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, 144773 + ... + 145334.

It is an arithmetic number, because the mean of its divisors is an integer number (20452614).

Almost surely, 2^81520067 is an apocalyptic number.

81520067 is a deficient number, since it is larger than the sum of its proper divisors (290389).

81520067 is a wasteful number, since it uses less digits than its factorization.

81520067 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290388.

The product of its (nonzero) digits is 3360, while the sum is 29.

The square root of 81520067 is about 9028.8463825674. The cubic root of 81520067 is about 433.5989042055.

The spelling of 81520067 in words is "eighty-one million, five hundred twenty thousand, sixty-seven".