99981389 has 2 divisors, whose sum is σ = 99981390. Its totient is φ = 99981388.

The previous prime is 99981377. The next prime is 99981421. The reversal of 99981389 is 98318999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 63282025 + 36699364 = 7955^2 + 6058^2 .

It is an emirp because it is prime and its reverse (98318999) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-99981389 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 (99989389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49990694 + 49990695.

It is an arithmetic number, because the mean of its divisors is an integer number (49990695).

Almost surely, 2^99981389 is an apocalyptic number.

It is an amenable number.

99981389 is a deficient number, since it is larger than the sum of its proper divisors (1).

99981389 is an equidigital number, since it uses as much as digits as its factorization.

99981389 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1259712, while the sum is 56.

The square root of 99981389 is about 9999.0694066998. The cubic root of 99981389 is about 464.1300867048.

The spelling of 99981389 in words is "ninety-nine million, nine hundred eighty-one thousand, three hundred eighty-nine".