78215904 has 108 divisors (see below), whose sum is σ = 241002216. Its totient is φ = 24051456.

The previous prime is 78215897. The next prime is 78215909. The reversal of 78215904 is 40951287.

It is a super-2 number, since 2×78215904² = 12235455277074432, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78215909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 47869 + ... + 49475.

It is an arithmetic number, because the mean of its divisors is an integer number (2231502).

Almost surely, 2^78215904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 78215904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120501108).

78215904 is an abundant number, since it is smaller than the sum of its proper divisors (162786312).

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

78215904 is a wasteful number, since it uses less digits than its factorization.

78215904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1649 (or 1625 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 78215904 is about 8843.9755766284. The cubic root of 78215904 is about 427.6597289652.

The spelling of 78215904 in words is "seventy-eight million, two hundred fifteen thousand, nine hundred four".