77819940 has 180 divisors, whose sum is σ = 269010588. Its totient is φ = 18817920.

The previous prime is 77819933. The next prime is 77819941. The reversal of 77819940 is 4991877.

It can be written as a sum of positive squares in 2 ways, for example, as 40144896 + 37675044 = 6336^2 + 6138^2 .

It is a tau number, because it is divible by the number of its divisors (180).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (77819941) by changing a digit.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 195822 + ... + 196218.

Almost surely, 2^77819940 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77819940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (134505294).

77819940 is an abundant number, since it is smaller than the sum of its proper divisors (191190648).

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

77819940 is a wasteful number, since it uses less digits than its factorization.

77819940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 440 (or 418 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 45.

The square root of 77819940 is about 8821.5610863384. The cubic root of 77819940 is about 426.9368392484.

The spelling of 77819940 in words is "seventy-seven million, eight hundred nineteen thousand, nine hundred forty".