198499400821 has 2 divisors, whose sum is σ = 198499400822. Its totient is φ = 198499400820.

The previous prime is 198499400783. The next prime is 198499400833. The reversal of 198499400821 is 128004994891.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 197301202596 + 1198198225 = 444186^2 + 34615^2 .

It is a cyclic number.

It is not a de Polignac number, because 198499400821 - 2¹³ = 198499392629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (198499404821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99249700410 + 99249700411.

It is an arithmetic number, because the mean of its divisors is an integer number (99249700411).

Almost surely, 2^198499400821 is an apocalyptic number.

It is an amenable number.

198499400821 is a deficient number, since it is larger than the sum of its proper divisors (1).

198499400821 is an equidigital number, since it uses as much as digits as its factorization.

198499400821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1492992, while the sum is 55.

The spelling of 198499400821 in words is "one hundred ninety-eight billion, four hundred ninety-nine million, four hundred thousand, eight hundred twenty-one".