78551820 has 36 divisors (see below), whose sum is σ = 238274400. Its totient is φ = 20947104.

The previous prime is 78551813. The next prime is 78551843. The reversal of 78551820 is 2815587.

It is a tau number, because it is divible by the number of its divisors (36).

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

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 218020 + ... + 218379.

Almost surely, 2^78551820 is an apocalyptic number.

It is an amenable number.

78551820 is an abundant number, since it is smaller than the sum of its proper divisors (159722580).

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

78551820 is a wasteful number, since it uses less digits than its factorization.

78551820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 436414 (or 436409 counting only the distinct ones).

The product of its (nonzero) digits is 22400, while the sum is 36.

The square root of 78551820 is about 8862.9464626613. The cubic root of 78551820 is about 428.2710819446.

The spelling of 78551820 in words is "seventy-eight million, five hundred fifty-one thousand, eight hundred twenty".