1684561 has 2 divisors, whose sum is σ = 1684562. Its totient is φ = 1684560.

The previous prime is 1684549. The next prime is 1684577. The reversal of 1684561 is 1654861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1113025 + 571536 = 1055^2 + 756^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1684561 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1684511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 842280 + 842281.

It is an arithmetic number, because the mean of its divisors is an integer number (842281).

2^1684561 is an apocalyptic number.

It is an amenable number.

1684561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1684561 is an equidigital number, since it uses as much as digits as its factorization.

1684561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5760, while the sum is 31.

The square root of 1684561 is about 1297.9063910776. The cubic root of 1684561 is about 118.9859221159.

Subtracting from 1684561 its sum of digits (31), we obtain a triangular number (1684530 = T₁₈₃₅).

The spelling of 1684561 in words is "one million, six hundred eighty-four thousand, five hundred sixty-one".