990879509 has 2 divisors, whose sum is σ = 990879510. Its totient is φ = 990879508.

The previous prime is 990879497. The next prime is 990879517. The reversal of 990879509 is 905978099.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 840130225 + 150749284 = 28985^2 + 12278^2 .

It is a cyclic number.

It is not a de Polignac number, because 990879509 - 2¹⁶ = 990813973 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (990879529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495439754 + 495439755.

It is an arithmetic number, because the mean of its divisors is an integer number (495439755).

Almost surely, 2^990879509 is an apocalyptic number.

It is an amenable number.

990879509 is a deficient number, since it is larger than the sum of its proper divisors (1).

990879509 is an equidigital number, since it uses as much as digits as its factorization.

990879509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1837080, while the sum is 56.

The square root of 990879509 is about 31478.2386578411. The cubic root of 990879509 is about 996.9505466199.

The spelling of 990879509 in words is "nine hundred ninety million, eight hundred seventy-nine thousand, five hundred nine".