77642809 has 4 divisors (see below), whose sum is σ = 78107904. Its totient is φ = 77177716.

The previous prime is 77642753. The next prime is 77642819. The reversal of 77642809 is 90824677.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 77642809 - 2⁷ = 77642681 is a prime.

It is not an unprimeable number, because it can be changed into a prime (77642819) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 232297 + ... + 232630.

It is an arithmetic number, because the mean of its divisors is an integer number (19526976).

Almost surely, 2^77642809 is an apocalyptic number.

It is an amenable number.

77642809 is a deficient number, since it is larger than the sum of its proper divisors (465095).

77642809 is a wasteful number, since it uses less digits than its factorization.

77642809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 465094.

The product of its (nonzero) digits is 169344, while the sum is 43.

The square root of 77642809 is about 8811.5157038957. The cubic root of 77642809 is about 426.6126669806.

The spelling of 77642809 in words is "seventy-seven million, six hundred forty-two thousand, eight hundred nine".