77991949 has 4 divisors (see below), whose sum is σ = 89133664. Its totient is φ = 66850236.

The previous prime is 77991929. The next prime is 77991983. The reversal of 77991949 is 94919977.

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, and also an emirpimes, since its reverse is a distinct semiprime: 94919977 = 769 ⋅123433.

It is a cyclic number.

It is not a de Polignac number, because 77991949 - 2⁷ = 77991821 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 77991949.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77991929) 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, 5570847 + ... + 5570860.

It is an arithmetic number, because the mean of its divisors is an integer number (22283416).

Almost surely, 2^77991949 is an apocalyptic number.

It is an amenable number.

77991949 is a deficient number, since it is larger than the sum of its proper divisors (11141715).

77991949 is a wasteful number, since it uses less digits than its factorization.

77991949 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11141714.

The product of its digits is 1285956, while the sum is 55.

The square root of 77991949 is about 8831.3050564455. The cubic root of 77991949 is about 427.2511671618.

It can be divided in two parts, 7799 and 1949, that multiplied together give a palindrome (15200251).

The spelling of 77991949 in words is "seventy-seven million, nine hundred ninety-one thousand, nine hundred forty-nine".