9781012181 has 2 divisors, whose sum is σ = 9781012182. Its totient is φ = 9781012180.

The previous prime is 9781012139. The next prime is 9781012229. The reversal of 9781012181 is 1812101879.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9439871281 + 341140900 = 97159^2 + 18470^2 .

It is a cyclic number.

It is not a de Polignac number, because 9781012181 - 2¹⁴ = 9780995797 is a prime.

It is a super-2 number, since 2×9781012181² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9781012481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4890506090 + 4890506091.

It is an arithmetic number, because the mean of its divisors is an integer number (4890506091).

Almost surely, 2^9781012181 is an apocalyptic number.

It is an amenable number.

9781012181 is a deficient number, since it is larger than the sum of its proper divisors (1).

9781012181 is an equidigital number, since it uses as much as digits as its factorization.

9781012181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8064, while the sum is 38.

The square root of 9781012181 is about 98898.9998988867. Note that the first 3 decimals coincide. The cubic root of 9781012181 is about 2138.5919771712.

The spelling of 9781012181 in words is "nine billion, seven hundred eighty-one million, twelve thousand, one hundred eighty-one".