821880077 has 4 divisors (see below), whose sum is σ = 822432060. Its totient is φ = 821328096.

The previous prime is 821880053. The next prime is 821880109. The reversal of 821880077 is 770088128.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 551968036 + 269912041 = 23494^2 + 16429^2 .

It is a cyclic number.

It is not a de Polignac number, because 821880077 - 2⁶ = 821880013 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 (821880977) 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, 273752 + ... + 276737.

It is an arithmetic number, because the mean of its divisors is an integer number (205608015).

Almost surely, 2^821880077 is an apocalyptic number.

It is an amenable number.

821880077 is a deficient number, since it is larger than the sum of its proper divisors (551983).

821880077 is a wasteful number, since it uses less digits than its factorization.

821880077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 551982.

The product of its (nonzero) digits is 50176, while the sum is 41.

The square root of 821880077 is about 28668.4508999004. The cubic root of 821880077 is about 936.7049551575.

The spelling of 821880077 in words is "eight hundred twenty-one million, eight hundred eighty thousand, seventy-seven".