77643720 has 192 divisors, whose sum is σ = 314720640. Its totient is φ = 16128000.

The previous prime is 77643673. The next prime is 77643721. The reversal of 77643720 is 2734677.

77643720 is a `hidden beast` number, since 7 + 7 + 643 + 7 + 2 + 0 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (77643721) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 26320 + ... + 29120.

It is an arithmetic number, because the mean of its divisors is an integer number (1639170).

Almost surely, 2^77643720 is an apocalyptic number.

77643720 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 77643720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (157360320).

77643720 is an abundant number, since it is smaller than the sum of its proper divisors (237076920).

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

77643720 is a wasteful number, since it uses less digits than its factorization.

77643720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2836 (or 2829 counting only the distinct ones).

The product of its (nonzero) digits is 49392, while the sum is 36.

The square root of 77643720 is about 8811.5673974611. The cubic root of 77643720 is about 426.6143354872.

The spelling of 77643720 in words is "seventy-seven million, six hundred forty-three thousand, seven hundred twenty".