81800001 has 12 divisors (see below), whose sum is σ = 119326740. Its totient is φ = 53992800.

The previous prime is 81799987. The next prime is 81800051. The reversal of 81800001 is 10000818.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 51494976 + 30305025 = 7176^2 + 5505^2 .

It is not a de Polignac number, because 81800001 - 2¹¹ = 81797953 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81800051) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 44086 + ... + 45903.

It is an arithmetic number, because the mean of its divisors is an integer number (9943895).

Almost surely, 2^81800001 is an apocalyptic number.

It is an amenable number.

81800001 is a deficient number, since it is larger than the sum of its proper divisors (37526739).

81800001 is a wasteful number, since it uses less digits than its factorization.

81800001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90096 (or 90093 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

The square root of 81800001 is about 9044.3352989592. The cubic root of 81800001 is about 434.0946529167.

Adding to 81800001 its reverse (10000818), we get a palindrome (91800819).

The spelling of 81800001 in words is "eighty-one million, eight hundred thousand, one".