684537583622521 has 2 divisors, whose sum is σ = 684537583622522. Its totient is φ = 684537583622520.

The previous prime is 684537583622483. The next prime is 684537583622533. The reversal of 684537583622521 is 125226385735486.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 655359436800121 + 29178146822400 = 25599989^2 + 5401680^2 .

It is a cyclic number.

It is not a de Polignac number, because 684537583622521 - 2²⁵ = 684537550068089 is a prime.

It is not a weakly prime, because it can be changed into another prime (684537583622551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342268791811260 + 342268791811261.

It is an arithmetic number, because the mean of its divisors is an integer number (342268791811261).

Almost surely, 2^{684537583622521} is an apocalyptic number.

It is an amenable number.

684537583622521 is a deficient number, since it is larger than the sum of its proper divisors (1).

684537583622521 is an equidigital number, since it uses as much as digits as its factorization.

684537583622521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 580608000, while the sum is 67.

The spelling of 684537583622521 in words is "six hundred eighty-four trillion, five hundred thirty-seven billion, five hundred eighty-three million, six hundred twenty-two thousand, five hundred twenty-one".