78172640 has 216 divisors, whose sum is σ = 236575080. Its totient is φ = 24321024.

The previous prime is 78172639. The next prime is 78172643. The reversal of 78172640 is 4627187.

It is a happy number.

It is a super-2 number, since 2×78172640² = 12221923289139200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 78172640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78172643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1324931 + ... + 1324989.

It is an arithmetic number, because the mean of its divisors is an integer number (1095255).

Almost surely, 2^78172640 is an apocalyptic number.

78172640 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 78172640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118287540).

78172640 is an abundant number, since it is smaller than the sum of its proper divisors (158402440).

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

78172640 is a wasteful number, since it uses less digits than its factorization.

78172640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114 (or 86 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 35.

The square root of 78172640 is about 8841.5292794855. The cubic root of 78172640 is about 427.5808631504.

The spelling of 78172640 in words is "seventy-eight million, one hundred seventy-two thousand, six hundred forty".