1999646669 has 2 divisors, whose sum is σ = 1999646670. Its totient is φ = 1999646668.

The previous prime is 1999646653. The next prime is 1999646681. The reversal of 1999646669 is 9666469991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1426044169 + 573602500 = 37763^2 + 23950^2 .

It is an emirp because it is prime and its reverse (9666469991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1999646669 - 2⁴ = 1999646653 is a prime.

It is a super-2 number, since 2×1999646669² = 7997173601685591122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1999646639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999823334 + 999823335.

It is an arithmetic number, because the mean of its divisors is an integer number (999823335).

Almost surely, 2^1999646669 is an apocalyptic number.

It is an amenable number.

1999646669 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999646669 is an equidigital number, since it uses as much as digits as its factorization.

1999646669 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34012224, while the sum is 65.

The square root of 1999646669 is about 44717.4090148345. The cubic root of 1999646669 is about 1259.8468506645.

The spelling of 1999646669 in words is "one billion, nine hundred ninety-nine million, six hundred forty-six thousand, six hundred sixty-nine".