9991669 has 2 divisors, whose sum is σ = 9991670. Its totient is φ = 9991668.

The previous prime is 9991649. The next prime is 9991673. The reversal of 9991669 is 9661999.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9922500 + 69169 = 3150^2 + 263^2 .

It is a cyclic number.

It is not a de Polignac number, because 9991669 - 2¹⁵ = 9958901 is a prime.

It is a super-2 number, since 2×9991669² = 199666898811122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9991649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995834 + 4995835.

It is an arithmetic number, because the mean of its divisors is an integer number (4995835).

Almost surely, 2^9991669 is an apocalyptic number.

It is an amenable number.

9991669 is a deficient number, since it is larger than the sum of its proper divisors (1).

9991669 is an equidigital number, since it uses as much as digits as its factorization.

9991669 is an evil number, because the sum of its binary digits is even.

The product of its digits is 236196, while the sum is 49.

The square root of 9991669 is about 3160.9601389451. The cubic root of 9991669 is about 215.3836237297.

The spelling of 9991669 in words is "nine million, nine hundred ninety-one thousand, six hundred sixty-nine".