81000145 has 4 divisors (see below), whose sum is σ = 97200180. Its totient is φ = 64800112.

The previous prime is 81000113. The next prime is 81000149. The reversal of 81000145 is 54100018.

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 50794129 + 30206016 = 7127^2 + 5496^2 .

It is a cyclic number.

It is not a de Polignac number, because 81000145 - 2⁵ = 81000113 is a prime.

It is a super-2 number, since 2×81000145² = 13122046980042050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81000149) 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, 8100010 + ... + 8100019.

It is an arithmetic number, because the mean of its divisors is an integer number (24300045).

Almost surely, 2^81000145 is an apocalyptic number.

It is an amenable number.

81000145 is a deficient number, since it is larger than the sum of its proper divisors (16200035).

81000145 is a wasteful number, since it uses less digits than its factorization.

81000145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16200034.

The product of its (nonzero) digits is 160, while the sum is 19.

The square root of 81000145 is about 9000.0080555520. The cubic root of 81000145 is about 432.6751292725.

The spelling of 81000145 in words is "eighty-one million, one hundred forty-five", and thus it is an aban number.