81177981 has 8 divisors (see below), whose sum is σ = 108710880. Its totient is φ = 53881872.

The previous prime is 81177979. The next prime is 81177997. The reversal of 81177981 is 18977118.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81177981 - 2¹ = 81177979 is a prime.

It is a super-2 number, since 2×81177981² = 13179729198472722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81177961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 58395 + ... + 59768.

It is an arithmetic number, because the mean of its divisors is an integer number (13588860).

Almost surely, 2^81177981 is an apocalyptic number.

It is an amenable number.

81177981 is a deficient number, since it is larger than the sum of its proper divisors (27532899).

81177981 is a wasteful number, since it uses less digits than its factorization.

81177981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118395.

The product of its digits is 28224, while the sum is 42.

The square root of 81177981 is about 9009.8824076677. The cubic root of 81177981 is about 432.9915442277.

The spelling of 81177981 in words is "eighty-one million, one hundred seventy-seven thousand, nine hundred eighty-one".