81812601 has 12 divisors (see below), whose sum is σ = 127264228. Its totient is φ = 50346144.

The previous prime is 81812581. The next prime is 81812603. The reversal of 81812601 is 10621818.

It can be written as a sum of positive squares in 2 ways, for example, as 12257001 + 69555600 = 3501^2 + 8340^2 .

It is not a de Polignac number, because 81812601 - 2¹⁰ = 81811577 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81812603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 349510 + ... + 349743.

Almost surely, 2^81812601 is an apocalyptic number.

It is an amenable number.

81812601 is a deficient number, since it is larger than the sum of its proper divisors (45451627).

81812601 is a wasteful number, since it uses less digits than its factorization.

81812601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 699272 (or 699269 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 27.

The square root of 81812601 is about 9045.0318407400. The cubic root of 81812601 is about 434.1169402506.

The spelling of 81812601 in words is "eighty-one million, eight hundred twelve thousand, six hundred one".