81080651781 has 20 divisors (see below), whose sum is σ = 122826410784. Its totient is φ = 53292443400.

The previous prime is 81080651761. The next prime is 81080651801. The reversal of 81080651781 is 18715608018.

It is an interprime number because it is at equal distance from previous prime (81080651761) and next prime (81080651801).

It is not a de Polignac number, because 81080651781 - 2⁷ = 81080651653 is a prime.

It is a super-2 number, since 2×81080651781² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81080651731) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 7043515 + ... + 7055016.

Almost surely, 2^81080651781 is an apocalyptic number.

81080651781 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

81080651781 is a deficient number, since it is larger than the sum of its proper divisors (41745759003).

81080651781 is a wasteful number, since it uses less digits than its factorization.

81080651781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14098614 (or 14098605 counting only the distinct ones).

The product of its (nonzero) digits is 107520, while the sum is 45.

The spelling of 81080651781 in words is "eighty-one billion, eighty million, six hundred fifty-one thousand, seven hundred eighty-one".