77216720 has 80 divisors (see below), whose sum is σ = 217271808. Its totient is φ = 24913920.

The previous prime is 77216693. The next prime is 77216747. The reversal of 77216720 is 2761277.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (77216693) and next prime (77216747).

It is a tau number, because it is divible by the number of its divisors (80).

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 15 ways as a sum of consecutive naturals, for example, 5465 + ... + 13575.

Almost surely, 2^77216720 is an apocalyptic number.

77216720 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77216720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108635904).

77216720 is an abundant number, since it is smaller than the sum of its proper divisors (140055088).

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

77216720 is a wasteful number, since it uses less digits than its factorization.

77216720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8148 (or 8142 counting only the distinct ones).

The product of its (nonzero) digits is 8232, while the sum is 32.

The square root of 77216720 is about 8787.3044786214. The cubic root of 77216720 is about 425.8308452854.

Adding to 77216720 its reverse (2761277), we get a palindrome (79977997).

It can be divided in two parts, 7721 and 6720, that added together give a palindrome (14441).

The spelling of 77216720 in words is "seventy-seven million, two hundred sixteen thousand, seven hundred twenty".