77646420 has 36 divisors (see below), whose sum is σ = 235528020. Its totient is φ = 20705664.

The previous prime is 77646389. The next prime is 77646421. The reversal of 77646420 is 2464677.

77646420 is a `hidden beast` number, since 7 + 7 + 6 + 4 + 642 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 44675856 + 32970564 = 6684^2 + 5742^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77646421) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 215505 + ... + 215864.

It is an arithmetic number, because the mean of its divisors is an integer number (6542445).

Almost surely, 2^77646420 is an apocalyptic number.

It is an amenable number.

77646420 is an abundant number, since it is smaller than the sum of its proper divisors (157881600).

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

77646420 is a wasteful number, since it uses less digits than its factorization.

77646420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 431384 (or 431379 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 36.

The square root of 77646420 is about 8811.7206038321. The cubic root of 77646420 is about 426.6192804905.

The spelling of 77646420 in words is "seventy-seven million, six hundred forty-six thousand, four hundred twenty".