81814521 has 8 divisors (see below), whose sum is σ = 109248480. Its totient is φ = 54461792.

The previous prime is 81814517. The next prime is 81814529. The reversal of 81814521 is 12541818.

It is a happy number.

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 81814521 - 2² = 81814517 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (81814529) 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, 17916 + ... + 22013.

It is an arithmetic number, because the mean of its divisors is an integer number (13656060).

Almost surely, 2^81814521 is an apocalyptic number.

It is an amenable number.

81814521 is a deficient number, since it is larger than the sum of its proper divisors (27433959).

81814521 is a wasteful number, since it uses less digits than its factorization.

81814521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40615.

The product of its digits is 2560, while the sum is 30.

The square root of 81814521 is about 9045.1379757304. The cubic root of 81814521 is about 434.1203362148.

The spelling of 81814521 in words is "eighty-one million, eight hundred fourteen thousand, five hundred twenty-one".