6699550021 has 2 divisors, whose sum is σ = 6699550022. Its totient is φ = 6699550020.

The previous prime is 6699550007. The next prime is 6699550037. The reversal of 6699550021 is 1200559966.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5053219396 + 1646330625 = 71086^2 + 40575^2 .

It is a cyclic number.

It is not a de Polignac number, because 6699550021 - 2²³ = 6691161413 is a prime.

It is a super-2 number, since 2×6699550021² = 89767940967762200882, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 6699550021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6699550051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3349775010 + 3349775011.

It is an arithmetic number, because the mean of its divisors is an integer number (3349775011).

Almost surely, 2^6699550021 is an apocalyptic number.

It is an amenable number.

6699550021 is a deficient number, since it is larger than the sum of its proper divisors (1).

6699550021 is an equidigital number, since it uses as much as digits as its factorization.

6699550021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 145800, while the sum is 43.

The square root of 6699550021 is about 81850.7789883517. The cubic root of 6699550021 is about 1885.1614259943.

The spelling of 6699550021 in words is "six billion, six hundred ninety-nine million, five hundred fifty thousand, twenty-one".