77638905 has 40 divisors (see below), whose sum is σ = 141840072. Its totient is φ = 40614912.

The previous prime is 77638903. The next prime is 77638919. The reversal of 77638905 is 50983677.

It is a happy number.

77638905 is a `hidden beast` number, since 7 + 7 + 638 + 9 + 0 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 480249 + 77158656 = 693^2 + 8784^2 .

It is not a de Polignac number, because 77638905 - 2¹ = 77638903 is a prime.

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 (77638903) 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 39 ways as a sum of consecutive naturals, for example, 19657 + ... + 23273.

Almost surely, 2^77638905 is an apocalyptic number.

It is an amenable number.

77638905 is a deficient number, since it is larger than the sum of its proper divisors (64201167).

77638905 is a wasteful number, since it uses less digits than its factorization.

77638905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3687 (or 3678 counting only the distinct ones).

The product of its (nonzero) digits is 317520, while the sum is 45.

The square root of 77638905 is about 8811.2941728216. The cubic root of 77638905 is about 426.6055166134.

The spelling of 77638905 in words is "seventy-seven million, six hundred thirty-eight thousand, nine hundred five".