77778993 has 4 divisors (see below), whose sum is σ = 103705328. Its totient is φ = 51852660.

The previous prime is 77778983. The next prime is 77779001. The reversal of 77778993 is 39987777.

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 not a de Polignac number, because 77778993 - 2¹⁶ = 77713457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77778983) 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, 12963163 + ... + 12963168.

It is an arithmetic number, because the mean of its divisors is an integer number (25926332).

Almost surely, 2^77778993 is an apocalyptic number.

It is an amenable number.

77778993 is a deficient number, since it is larger than the sum of its proper divisors (25926335).

77778993 is a wasteful number, since it uses less digits than its factorization.

77778993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25926334.

The product of its digits is 4667544, while the sum is 57.

The square root of 77778993 is about 8819.2399332369. The cubic root of 77778993 is about 426.8619447770.

The spelling of 77778993 in words is "seventy-seven million, seven hundred seventy-eight thousand, nine hundred ninety-three".