78991146 has 64 divisors (see below), whose sum is σ = 200188800. Its totient is φ = 22871808.

The previous prime is 78991141. The next prime is 78991153. The reversal of 78991146 is 64119987.

It is a happy number.

It is a super-2 number, since 2×78991146² = 12479202292786632, which contains 22 as substring.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (78991141) 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, 8625 + ... + 15243.

It is an arithmetic number, because the mean of its divisors is an integer number (3127950).

Almost surely, 2^78991146 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 78991146, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100094400).

78991146 is an abundant number, since it is smaller than the sum of its proper divisors (121197654).

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

78991146 is a wasteful number, since it uses less digits than its factorization.

78991146 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6660 (or 6654 counting only the distinct ones).

The product of its digits is 108864, while the sum is 45.

The square root of 78991146 is about 8887.6963269455. The cubic root of 78991146 is about 429.0680121032.

It can be divided in two parts, 7899 and 1146, that added together give a triangular number (9045 = T₁₃₄).

The spelling of 78991146 in words is "seventy-eight million, nine hundred ninety-one thousand, one hundred forty-six".