77043821 has 4 divisors (see below), whose sum is σ = 78497532. Its totient is φ = 75590112.

The previous prime is 77043817. The next prime is 77043823. The reversal of 77043821 is 12834077.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12834077 = 379 ⋅33863.

It can be written as a sum of positive squares in 2 ways, for example, as 18826921 + 58216900 = 4339^2 + 7630^2 .

It is a cyclic number.

It is not a de Polignac number, because 77043821 - 2² = 77043817 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77043823) 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, 726776 + ... + 726881.

It is an arithmetic number, because the mean of its divisors is an integer number (19624383).

Almost surely, 2^77043821 is an apocalyptic number.

It is an amenable number.

77043821 is a deficient number, since it is larger than the sum of its proper divisors (1453711).

77043821 is a wasteful number, since it uses less digits than its factorization.

77043821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1453710.

The product of its (nonzero) digits is 9408, while the sum is 32.

The square root of 77043821 is about 8777.4609654501. The cubic root of 77043821 is about 425.5127762258.

Adding to 77043821 its reverse (12834077), we get a palindrome (89877898).

The spelling of 77043821 in words is "seventy-seven million, forty-three thousand, eight hundred twenty-one".