81240861 has 32 divisors (see below), whose sum is σ = 121968000. Its totient is φ = 47755008.

The previous prime is 81240857. The next prime is 81240871. The reversal of 81240861 is 16804218.

It is not a de Polignac number, because 81240861 - 2² = 81240857 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81240821) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 122950 + ... + 123608.

It is an arithmetic number, because the mean of its divisors is an integer number (3811500).

Almost surely, 2^81240861 is an apocalyptic number.

It is an amenable number.

81240861 is a deficient number, since it is larger than the sum of its proper divisors (40727139).

81240861 is a wasteful number, since it uses less digits than its factorization.

81240861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 813.

The product of its (nonzero) digits is 3072, while the sum is 30.

The square root of 81240861 is about 9013.3712338947. The cubic root of 81240861 is about 433.1033129658.

The spelling of 81240861 in words is "eighty-one million, two hundred forty thousand, eight hundred sixty-one".