80947781 has 4 divisors (see below), whose sum is σ = 80980332. Its totient is φ = 80915232.

The previous prime is 80947777. The next prime is 80947799. The reversal of 80947781 is 18774908.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 44102881 + 36844900 = 6641^2 + 6070^2 .

It is a cyclic number.

It is not a de Polignac number, because 80947781 - 2² = 80947777 is a prime.

It is a super-2 number, since 2×80947781² = 13105086497647922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (80947721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12206 + ... + 17631.

It is an arithmetic number, because the mean of its divisors is an integer number (20245083).

Almost surely, 2^80947781 is an apocalyptic number.

It is an amenable number.

80947781 is a deficient number, since it is larger than the sum of its proper divisors (32551).

80947781 is a wasteful number, since it uses less digits than its factorization.

80947781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32550.

The product of its (nonzero) digits is 112896, while the sum is 44.

The square root of 80947781 is about 8997.0984767313. The cubic root of 80947781 is about 432.5818723017.

The spelling of 80947781 in words is "eighty million, nine hundred forty-seven thousand, seven hundred eighty-one".