1801336661 has 2 divisors, whose sum is σ = 1801336662. Its totient is φ = 1801336660.

The previous prime is 1801336613. The next prime is 1801336699. The reversal of 1801336661 is 1666331081.

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., 912402436 + 888934225 = 30206^2 + 29815^2 .

It is a cyclic number.

It is not a de Polignac number, because 1801336661 - 2²² = 1797142357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1801336861) 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, 900668330 + 900668331.

It is an arithmetic number, because the mean of its divisors is an integer number (900668331).

Almost surely, 2^1801336661 is an apocalyptic number.

It is an amenable number.

1801336661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1801336661 is an equidigital number, since it uses as much as digits as its factorization.

1801336661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 1801336661 is about 42442.1566487849. The cubic root of 1801336661 is about 1216.7414298796.

The spelling of 1801336661 in words is "one billion, eight hundred one million, three hundred thirty-six thousand, six hundred sixty-one".