990881917 has 2 divisors, whose sum is σ = 990881918. Its totient is φ = 990881916.

The previous prime is 990881909. The next prime is 990881921. The reversal of 990881917 is 719188099.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 988096356 + 2785561 = 31434^2 + 1669^2 .

It is a cyclic number.

It is not a de Polignac number, because 990881917 - 2³ = 990881909 is a prime.

It is a congruent number.

It is a weakly prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495440958 + 495440959.

It is an arithmetic number, because the mean of its divisors is an integer number (495440959).

Almost surely, 2^990881917 is an apocalyptic number.

It is an amenable number.

990881917 is a deficient number, since it is larger than the sum of its proper divisors (1).

990881917 is an equidigital number, since it uses as much as digits as its factorization.

990881917 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 326592, while the sum is 52.

The square root of 990881917 is about 31478.2769064636. The cubic root of 990881917 is about 996.9513542038.

The spelling of 990881917 in words is "nine hundred ninety million, eight hundred eighty-one thousand, nine hundred seventeen".