99971813 has 2 divisors, whose sum is σ = 99971814. Its totient is φ = 99971812.

The previous prime is 99971803. The next prime is 99971827. The reversal of 99971813 is 31817999.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 86081284 + 13890529 = 9278^2 + 3727^2 .

It is a cyclic number.

It is not a de Polignac number, because 99971813 - 2⁴ = 99971797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (99971803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49985906 + 49985907.

It is an arithmetic number, because the mean of its divisors is an integer number (49985907).

Almost surely, 2^99971813 is an apocalyptic number.

It is an amenable number.

99971813 is a deficient number, since it is larger than the sum of its proper divisors (1).

99971813 is an equidigital number, since it uses as much as digits as its factorization.

99971813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 122472, while the sum is 47.

The square root of 99971813 is about 9998.5905506726. The cubic root of 99971813 is about 464.1152684416.

The spelling of 99971813 in words is "ninety-nine million, nine hundred seventy-one thousand, eight hundred thirteen".