6989921 has 2 divisors, whose sum is σ = 6989922. Its totient is φ = 6989920.

The previous prime is 6989869. The next prime is 6989923. The reversal of 6989921 is 1299896.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6964321 + 25600 = 2639^2 + 160^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6989921 is a prime.

It is a Sophie Germain prime.

Together with 6989923, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (6989923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3494960 + 3494961.

It is an arithmetic number, because the mean of its divisors is an integer number (3494961).

Almost surely, 2^6989921 is an apocalyptic number.

It is an amenable number.

6989921 is a deficient number, since it is larger than the sum of its proper divisors (1).

6989921 is an equidigital number, since it uses as much as digits as its factorization.

6989921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 69984, while the sum is 44.

The square root of 6989921 is about 2643.8458729661. The cubic root of 6989921 is about 191.2012625892.

The spelling of 6989921 in words is "six million, nine hundred eighty-nine thousand, nine hundred twenty-one".