99998021 has 2 divisors, whose sum is σ = 99998022. Its totient is φ = 99998020.

The previous prime is 99997981. The next prime is 99998051. The reversal of 99998021 is 12089999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 97732996 + 2265025 = 9886^2 + 1505^2 .

It is an emirp because it is prime and its reverse (12089999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 99998021 - 2⁶ = 99997957 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (99998051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49999010 + 49999011.

It is an arithmetic number, because the mean of its divisors is an integer number (49999011).

Almost surely, 2^99998021 is an apocalyptic number.

It is an amenable number.

99998021 is a deficient number, since it is larger than the sum of its proper divisors (1).

99998021 is an equidigital number, since it uses as much as digits as its factorization.

99998021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 104976, while the sum is 47.

The square root of 99998021 is about 9999.9010495104. The cubic root of 99998021 is about 464.1558214396.

It can be divided in two parts, 999980 and 21, that added together give a palindrome (1000001).

The spelling of 99998021 in words is "ninety-nine million, nine hundred ninety-eight thousand, twenty-one".