1781631081 has 12 divisors (see below), whose sum is σ = 2573833860. Its totient is φ = 1187584800.

The previous prime is 1781631077. The next prime is 1781631091. The reversal of 1781631081 is 1801361871.

It is a happy number.

1781631081 is a `hidden beast` number, since 17 + 8 + 1 + 631 + 0 + 8 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 428862681 + 1352768400 = 20709^2 + 36780^2 .

It is not a de Polignac number, because 1781631081 - 2² = 1781631077 is a prime.

It is a super-2 number, since 2×1781631081² = 6348418617570457122, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1781631091) 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, 110431 + ... + 125531.

It is an arithmetic number, because the mean of its divisors is an integer number (214486155).

Almost surely, 2^1781631081 is an apocalyptic number.

It is an amenable number.

1781631081 is a deficient number, since it is larger than the sum of its proper divisors (792202779).

1781631081 is a wasteful number, since it uses less digits than its factorization.

1781631081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28216 (or 28213 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 1781631081 is about 42209.3719569481. The cubic root of 1781631081 is about 1212.2883365389.

The spelling of 1781631081 in words is "one billion, seven hundred eighty-one million, six hundred thirty-one thousand, eighty-one".