78891720 has 32 divisors (see below), whose sum is σ = 236675520. Its totient is φ = 21037760.

The previous prime is 78891697. The next prime is 78891731. The reversal of 78891720 is 2719887.

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, 328596 + ... + 328835.

It is an arithmetic number, because the mean of its divisors is an integer number (7396110).

Almost surely, 2^78891720 is an apocalyptic number.

It is an amenable number.

78891720 is an abundant number, since it is smaller than the sum of its proper divisors (157783800).

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

78891720 is a wasteful number, since it uses less digits than its factorization.

78891720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 657445 (or 657441 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 42.

The square root of 78891720 is about 8882.1011027797. The cubic root of 78891720 is about 428.8879141650.

The spelling of 78891720 in words is "seventy-eight million, eight hundred ninety-one thousand, seven hundred twenty".