100021993 has 2 divisors, whose sum is σ = 100021994. Its totient is φ = 100021992.

The previous prime is 100021981. The next prime is 100022003. The reversal of 100021993 is 399120001.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 99361024 + 660969 = 9968^2 + 813^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-100021993 is a prime.

It is not a weakly prime, because it can be changed into another prime (100021973) 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, 50010996 + 50010997.

It is an arithmetic number, because the mean of its divisors is an integer number (50010997).

Almost surely, 2^100021993 is an apocalyptic number.

It is an amenable number.

100021993 is a deficient number, since it is larger than the sum of its proper divisors (1).

100021993 is an equidigital number, since it uses as much as digits as its factorization.

100021993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 486, while the sum is 25.

The square root of 100021993 is about 10001.0995895451. The cubic root of 100021993 is about 464.1929083548.

Adding to 100021993 its reverse (399120001), we get a palindrome (499141994).

The spelling of 100021993 in words is "one hundred million, twenty-one thousand, nine hundred ninety-three".