77921771 has 4 divisors (see below), whose sum is σ = 79822344. Its totient is φ = 76021200.

The previous prime is 77921759. The next prime is 77921773. The reversal of 77921771 is 17712977.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 17712977 = 4157 ⋅4261.

It is a cyclic number.

It is not a de Polignac number, because 77921771 - 2¹⁰ = 77920747 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41), and also a Moran number because the ratio is a prime number: 1900531 = 77921771 / (7 + 7 + 9 + 2 + 1 + 7 + 7 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77921773) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 950225 + ... + 950306.

It is an arithmetic number, because the mean of its divisors is an integer number (19955586).

Almost surely, 2^77921771 is an apocalyptic number.

77921771 is a deficient number, since it is larger than the sum of its proper divisors (1900573).

77921771 is a wasteful number, since it uses less digits than its factorization.

77921771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1900572.

The product of its digits is 43218, while the sum is 41.

The square root of 77921771 is about 8827.3309103035. The cubic root of 77921771 is about 427.1229802977.

The spelling of 77921771 in words is "seventy-seven million, nine hundred twenty-one thousand, seven hundred seventy-one".