81687243 has 8 divisors (see below), whose sum is σ = 118817856. Its totient is φ = 49507400.

The previous prime is 81687241. The next prime is 81687253. The reversal of 81687243 is 34278618.

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

It is a cyclic number.

It is not a de Polignac number, because 81687243 - 2¹ = 81687241 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81687241) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1237653 + ... + 1237718.

It is an arithmetic number, because the mean of its divisors is an integer number (14852232).

Almost surely, 2^81687243 is an apocalyptic number.

81687243 is a deficient number, since it is larger than the sum of its proper divisors (37130613).

81687243 is a wasteful number, since it uses less digits than its factorization.

81687243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2475385.

The product of its digits is 64512, while the sum is 39.

The square root of 81687243 is about 9038.0995236831. The cubic root of 81687243 is about 433.8951005438.

The spelling of 81687243 in words is "eighty-one million, six hundred eighty-seven thousand, two hundred forty-three".