6997355921 has 2 divisors, whose sum is σ = 6997355922. Its totient is φ = 6997355920.

The previous prime is 6997355917. The next prime is 6997355923. The reversal of 6997355921 is 1295537996.

It is a happy number.

6997355921 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5207642896 + 1789713025 = 72164^2 + 42305^2 .

It is a cyclic number.

It is not a de Polignac number, because 6997355921 - 2² = 6997355917 is a prime.

Together with 6997355923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (6997355923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3498677960 + 3498677961.

It is an arithmetic number, because the mean of its divisors is an integer number (3498677961).

Almost surely, 2^6997355921 is an apocalyptic number.

It is an amenable number.

6997355921 is a deficient number, since it is larger than the sum of its proper divisors (1).

6997355921 is an equidigital number, since it uses as much as digits as its factorization.

6997355921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4592700, while the sum is 56.

The square root of 6997355921 is about 83650.1997666473. The cubic root of 6997355921 is about 1912.6902980990.

The spelling of 6997355921 in words is "six billion, nine hundred ninety-seven million, three hundred fifty-five thousand, nine hundred twenty-one".