1999900549 has 2 divisors, whose sum is σ = 1999900550. Its totient is φ = 1999900548.

The previous prime is 1999900543. The next prime is 1999900561. The reversal of 1999900549 is 9450099991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1116027649 + 883872900 = 33407^2 + 29730^2 .

It is a cyclic number.

It is not a de Polignac number, because 1999900549 - 2³ = 1999900541 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1999900549.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1999900541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999950274 + 999950275.

It is an arithmetic number, because the mean of its divisors is an integer number (999950275).

Almost surely, 2^1999900549 is an apocalyptic number.

It is an amenable number.

1999900549 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999900549 is an equidigital number, since it uses as much as digits as its factorization.

1999900549 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1180980, while the sum is 55.

The square root of 1999900549 is about 44720.2476401909. The cubic root of 1999900549 is about 1259.9001661473.

The spelling of 1999900549 in words is "one billion, nine hundred ninety-nine million, nine hundred thousand, five hundred forty-nine".