77979999 has 4 divisors (see below), whose sum is σ = 103973336. Its totient is φ = 51986664.

The previous prime is 77979983. The next prime is 77980033. The reversal of 77979999 is 99997977.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99997977 = 3 ⋅33332659.

It is not a de Polignac number, because 77979999 - 2⁴ = 77979983 is a prime.

It is a Duffinian number.

77979999 is a modest number, since divided by 9999 gives 7797 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77979919) 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, 12996664 + ... + 12996669.

It is an arithmetic number, because the mean of its divisors is an integer number (25993334).

Almost surely, 2^77979999 is an apocalyptic number.

77979999 is a deficient number, since it is larger than the sum of its proper divisors (25993337).

77979999 is a wasteful number, since it uses less digits than its factorization.

77979999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25993336.

The product of its digits is 20253807, while the sum is 66.

The square root of 77979999 is about 8830.6284600814. The cubic root of 77979999 is about 427.2293447716.

The spelling of 77979999 in words is "seventy-seven million, nine hundred seventy-nine thousand, nine hundred ninety-nine".