6899389921 has 2 divisors, whose sum is σ = 6899389922. Its totient is φ = 6899389920.

The previous prime is 6899389919. The next prime is 6899389927. The reversal of 6899389921 is 1299839986.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4232803600 + 2666586321 = 65060^2 + 51639^2 .

It is a cyclic number.

It is not a de Polignac number, because 6899389921 - 2¹ = 6899389919 is a prime.

Together with 6899389919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (6899389927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3449694960 + 3449694961.

It is an arithmetic number, because the mean of its divisors is an integer number (3449694961).

Almost surely, 2^6899389921 is an apocalyptic number.

It is an amenable number.

6899389921 is a deficient number, since it is larger than the sum of its proper divisors (1).

6899389921 is an equidigital number, since it uses as much as digits as its factorization.

6899389921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15116544, while the sum is 64.

The square root of 6899389921 is about 83062.5663039615. The cubic root of 6899389921 is about 1903.7221513657.

The spelling of 6899389921 in words is "six billion, eight hundred ninety-nine million, three hundred eighty-nine thousand, nine hundred twenty-one".