81678621 has 8 divisors (see below), whose sum is σ = 111222144. Its totient is φ = 53293760.

The previous prime is 81678607. The next prime is 81678637. The reversal of 81678621 is 12687618.

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 81678621 - 2¹⁵ = 81645853 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81678621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81679621) 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, 289500 + ... + 289781.

It is an arithmetic number, because the mean of its divisors is an integer number (13902768).

Almost surely, 2^81678621 is an apocalyptic number.

It is an amenable number.

81678621 is a deficient number, since it is larger than the sum of its proper divisors (29543523).

81678621 is a wasteful number, since it uses less digits than its factorization.

81678621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 579331.

The product of its digits is 32256, while the sum is 39.

The square root of 81678621 is about 9037.6225302897. The cubic root of 81678621 is about 433.8798342874.

The spelling of 81678621 in words is "eighty-one million, six hundred seventy-eight thousand, six hundred twenty-one".