78128220 has 24 divisors (see below), whose sum is σ = 218759184. Its totient is φ = 20834176.

The previous prime is 78128203. The next prime is 78128221. The reversal of 78128220 is 2282187.

It is a happy number.

It is a super-2 number, since 2×78128220² = 12208037520736800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78128221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 651009 + ... + 651128.

It is an arithmetic number, because the mean of its divisors is an integer number (9114966).

Almost surely, 2^78128220 is an apocalyptic number.

It is an amenable number.

78128220 is an abundant number, since it is smaller than the sum of its proper divisors (140630964).

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

78128220 is a wasteful number, since it uses less digits than its factorization.

78128220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1302149 (or 1302147 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 78128220 is about 8839.0169136618. The cubic root of 78128220 is about 427.4998597859.

The spelling of 78128220 in words is "seventy-eight million, one hundred twenty-eight thousand, two hundred twenty".