6899497921 has 2 divisors, whose sum is σ = 6899497922. Its totient is φ = 6899497920.

The previous prime is 6899497867. The next prime is 6899497931. The reversal of 6899497921 is 1297949986.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3745440000 + 3154057921 = 61200^2 + 56161^2 .

It is a cyclic number.

It is not a de Polignac number, because 6899497921 - 2²⁵ = 6865943489 is a prime.

It is not a weakly prime, because it can be changed into another prime (6899497931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3449748960 + 3449748961.

It is an arithmetic number, because the mean of its divisors is an integer number (3449748961).

Almost surely, 2^6899497921 is an apocalyptic number.

It is an amenable number.

6899497921 is a deficient number, since it is larger than the sum of its proper divisors (1).

6899497921 is an equidigital number, since it uses as much as digits as its factorization.

6899497921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17635968, while the sum is 64.

The square root of 6899497921 is about 83063.2164137652. The cubic root of 6899497921 is about 1903.7320846555.

The spelling of 6899497921 in words is "six billion, eight hundred ninety-nine million, four hundred ninety-seven thousand, nine hundred twenty-one".