1550661811 has 2 divisors, whose sum is σ = 1550661812. Its totient is φ = 1550661810.

The previous prime is 1550661809. The next prime is 1550661941. The reversal of 1550661811 is 1181660551.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (1181660551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1550661811 - 2¹ = 1550661809 is a prime.

Together with 1550661809, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1550664811) 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, 775330905 + 775330906.

It is an arithmetic number, because the mean of its divisors is an integer number (775330906).

Almost surely, 2^1550661811 is an apocalyptic number.

1550661811 is a deficient number, since it is larger than the sum of its proper divisors (1).

1550661811 is an equidigital number, since it uses as much as digits as its factorization.

1550661811 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7200, while the sum is 34.

The square root of 1550661811 is about 39378.4434811738. The cubic root of 1550661811 is about 1157.4592157073.

The spelling of 1550661811 in words is "one billion, five hundred fifty million, six hundred sixty-one thousand, eight hundred eleven".