77943821 has 16 divisors (see below), whose sum is σ = 81753408. Its totient is φ = 74256000.

The previous prime is 77943809. The next prime is 77943823. The reversal of 77943821 is 12834977.

It is a cyclic number.

It is not a de Polignac number, because 77943821 - 2¹⁰ = 77942797 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77943823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 568865 + ... + 569001.

It is an arithmetic number, because the mean of its divisors is an integer number (5109588).

Almost surely, 2^77943821 is an apocalyptic number.

It is an amenable number.

77943821 is a deficient number, since it is larger than the sum of its proper divisors (3809587).

77943821 is a wasteful number, since it uses less digits than its factorization.

77943821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 412.

The product of its digits is 84672, while the sum is 41.

The square root of 77943821 is about 8828.5797838610. The cubic root of 77943821 is about 427.1632650319.

The spelling of 77943821 in words is "seventy-seven million, nine hundred forty-three thousand, eight hundred twenty-one".