993888821 has 2 divisors, whose sum is σ = 993888822. Its totient is φ = 993888820.

The previous prime is 993888793. The next prime is 993888823. The reversal of 993888821 is 128888399.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 540795025 + 453093796 = 23255^2 + 21286^2 .

It is a cyclic number.

It is not a de Polignac number, because 993888821 - 2⁶ = 993888757 is a prime.

Together with 993888823, it forms a pair of twin primes.

It is a Chen prime.

It is a pancake number, because a pancake can be divided into 993888821 parts by 44584 straight cuts.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (993888823) 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 as a sum of consecutive naturals, namely, 496944410 + 496944411.

It is an arithmetic number, because the mean of its divisors is an integer number (496944411).

Almost surely, 2^993888821 is an apocalyptic number.

It is an amenable number.

993888821 is a deficient number, since it is larger than the sum of its proper divisors (1).

993888821 is an equidigital number, since it uses as much as digits as its factorization.

993888821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1990656, while the sum is 56.

The square root of 993888821 is about 31526.0022996891. The cubic root of 993888821 is about 997.9587765752.

The spelling of 993888821 in words is "nine hundred ninety-three million, eight hundred eighty-eight thousand, eight hundred twenty-one".