81678438072 has 128 divisors (see below), whose sum is σ = 282869107200. Its totient is φ = 21215174400.

The previous prime is 81678438071. The next prime is 81678438073. The reversal of 81678438072 is 27083487618.

It is a happy number.

81678438072 is a `hidden beast` number, since 81 + 67 + 8 + 438 + 0 + 72 = 666.

It is an interprime number because it is at equal distance from previous prime (81678438071) and next prime (81678438073).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81678438071) 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, 2438829 + ... + 2472092.

It is an arithmetic number, because the mean of its divisors is an integer number (2209914900).

Almost surely, 2^81678438072 is an apocalyptic number.

It is an amenable number.

81678438072 is an abundant number, since it is smaller than the sum of its proper divisors (201190669128).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81678438072 is a wasteful number, since it uses less digits than its factorization.

81678438072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4910954 (or 4910944 counting only the distinct ones).

The product of its (nonzero) digits is 3612672, while the sum is 54.

The spelling of 81678438072 in words is "eighty-one billion, six hundred seventy-eight million, four hundred thirty-eight thousand, seventy-two".