81003681 has 12 divisors (see below), whose sum is σ = 127642320. Its totient is φ = 49093080.

The previous prime is 81003667. The next prime is 81003697. The reversal of 81003681 is 18630018.

It is not a de Polignac number, because 81003681 - 2⁵ = 81003649 is a prime.

It is a super-2 number, since 2×81003681² = 13123192671099522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81003661) 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, 409011 + ... + 409208.

It is an arithmetic number, because the mean of its divisors is an integer number (10636860).

Almost surely, 2^81003681 is an apocalyptic number.

It is an amenable number.

81003681 is a deficient number, since it is larger than the sum of its proper divisors (46638639).

81003681 is a wasteful number, since it uses less digits than its factorization.

81003681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 818236 (or 818233 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 81003681 is about 9000.2044976767. The cubic root of 81003681 is about 432.6814252160.

Adding to 81003681 its reverse (18630018), we get a palindrome (99633699).

It can be divided in two parts, 8100 and 3681, that added together give a triangular number (11781 = T₁₅₃).

The spelling of 81003681 in words is "eighty-one million, three thousand, six hundred eighty-one".