1800698561 has 2 divisors, whose sum is σ = 1800698562. Its totient is φ = 1800698560.

The previous prime is 1800698539. The next prime is 1800698563. The reversal of 1800698561 is 1658960081.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1116562225 + 684136336 = 33415^2 + 26156^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1800698561 is a prime.

Together with 1800698563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1800698563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 900349280 + 900349281.

It is an arithmetic number, because the mean of its divisors is an integer number (900349281).

Almost surely, 2^1800698561 is an apocalyptic number.

It is an amenable number.

1800698561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1800698561 is an equidigital number, since it uses as much as digits as its factorization.

1800698561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 103680, while the sum is 44.

The square root of 1800698561 is about 42434.6386929358. The cubic root of 1800698561 is about 1216.5977413217.

The spelling of 1800698561 in words is "one billion, eight hundred million, six hundred ninety-eight thousand, five hundred sixty-one".