77648891 has 4 divisors (see below), whose sum is σ = 77805000. Its totient is φ = 77492784.

The previous prime is 77648887. The next prime is 77648899. The reversal of 77648891 is 19884677.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19884677 = 199 ⋅99923.

It is a cyclic number.

It is not a de Polignac number, because 77648891 - 2² = 77648887 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77648899) 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, 77306 + ... + 78303.

It is an arithmetic number, because the mean of its divisors is an integer number (19451250).

Almost surely, 2^77648891 is an apocalyptic number.

77648891 is a deficient number, since it is larger than the sum of its proper divisors (156109).

77648891 is a wasteful number, since it uses less digits than its factorization.

77648891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156108.

The product of its digits is 677376, while the sum is 50.

The square root of 77648891 is about 8811.8608136988. The cubic root of 77648891 is about 426.6238059838.

The spelling of 77648891 in words is "seventy-seven million, six hundred forty-eight thousand, eight hundred ninety-one".