78181638 has 8 divisors (see below), whose sum is σ = 156363288. Its totient is φ = 26060544.

The previous prime is 78181627. The next prime is 78181661. The reversal of 78181638 is 83618187.

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

78181638 is an admirable number.

It is a super-2 number, since 2×78181638² = 12224737040726088, which contains 22 as substring.

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

It is a self number, because there is not a number n which added to its sum of digits gives 78181638.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6515131 + ... + 6515142.

It is an arithmetic number, because the mean of its divisors is an integer number (19545411).

Almost surely, 2^78181638 is an apocalyptic number.

78181638 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

78181638 is a wasteful number, since it uses less digits than its factorization.

78181638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13030278.

The product of its digits is 64512, while the sum is 42.

The square root of 78181638 is about 8842.0381134668. The cubic root of 78181638 is about 427.5972679735.

The spelling of 78181638 in words is "seventy-eight million, one hundred eighty-one thousand, six hundred thirty-eight".