78215820 has 24 divisors (see below), whose sum is σ = 219004464. Its totient is φ = 20857536.

The previous prime is 78215791. The next prime is 78215833. The reversal of 78215820 is 2851287.

It is a super-2 number, since 2×78215820² = 12235428996544800, which contains 22 as substring.

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 7 ways as a sum of consecutive naturals, for example, 651739 + ... + 651858.

It is an arithmetic number, because the mean of its divisors is an integer number (9125186).

Almost surely, 2^78215820 is an apocalyptic number.

It is an amenable number.

78215820 is an abundant number, since it is smaller than the sum of its proper divisors (140788644).

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

78215820 is a wasteful number, since it uses less digits than its factorization.

78215820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1303609 (or 1303607 counting only the distinct ones).

The product of its (nonzero) digits is 8960, while the sum is 33.

The square root of 78215820 is about 8843.9708276317. The cubic root of 78215820 is about 427.6595758700.

The spelling of 78215820 in words is "seventy-eight million, two hundred fifteen thousand, eight hundred twenty".