81064645 has 4 divisors (see below), whose sum is σ = 97277580. Its totient is φ = 64851712.

The previous prime is 81064601. The next prime is 81064649. The reversal of 81064645 is 54646018.

81064645 = 6366² + 6367².

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

It can be written as a sum of positive squares in 2 ways, for example, as 40538689 + 40525956 = 6367^2 + 6366^2 .

It is a cyclic number.

It is not a de Polignac number, because 81064645 - 2²⁵ = 47510213 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81064645.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81064649) 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, 8106460 + ... + 8106469.

It is an arithmetic number, because the mean of its divisors is an integer number (24319395).

Almost surely, 2^81064645 is an apocalyptic number.

81064645 is the 6367-th centered square number.

It is an amenable number.

81064645 is a deficient number, since it is larger than the sum of its proper divisors (16212935).

81064645 is a wasteful number, since it uses less digits than its factorization.

81064645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16212934.

The product of its (nonzero) digits is 23040, while the sum is 34.

The square root of 81064645 is about 9003.5906726150. The cubic root of 81064645 is about 432.7899444644.

The spelling of 81064645 in words is "eighty-one million, sixty-four thousand, six hundred forty-five".