997821899 has 2 divisors, whose sum is σ = 997821900. Its totient is φ = 997821898.

The previous prime is 997821887. The next prime is 997821907. The reversal of 997821899 is 998128799.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-997821899 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (997821829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 498910949 + 498910950.

It is an arithmetic number, because the mean of its divisors is an integer number (498910950).

Almost surely, 2^997821899 is an apocalyptic number.

997821899 is a deficient number, since it is larger than the sum of its proper divisors (1).

997821899 is an equidigital number, since it uses as much as digits as its factorization.

997821899 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5878656, while the sum is 62.

The square root of 997821899 is about 31588.3190277672. The cubic root of 997821899 is about 999.2734385697.

The spelling of 997821899 in words is "nine hundred ninety-seven million, eight hundred twenty-one thousand, eight hundred ninety-nine".