81758065 has 8 divisors (see below), whose sum is σ = 99961128. Its totient is φ = 64172160.

The previous prime is 81758057. The next prime is 81758101. The reversal of 81758065 is 56085718.

It can be written as a sum of positive squares in 4 ways, for example, as 2405601 + 79352464 = 1551^2 + 8908^2 .

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

It is not a de Polignac number, because 81758065 - 2³ = 81758057 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 153996 + ... + 154525.

It is an arithmetic number, because the mean of its divisors is an integer number (12495141).

Almost surely, 2^81758065 is an apocalyptic number.

It is an amenable number.

81758065 is a deficient number, since it is larger than the sum of its proper divisors (18203063).

81758065 is a wasteful number, since it uses less digits than its factorization.

81758065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 308579.

The product of its (nonzero) digits is 67200, while the sum is 40.

The square root of 81758065 is about 9042.0166445323. The cubic root of 81758065 is about 434.0204585201.

The spelling of 81758065 in words is "eighty-one million, seven hundred fifty-eight thousand, sixty-five".