684639523 has 2 divisors, whose sum is σ = 684639524. Its totient is φ = 684639522.

The previous prime is 684639503. The next prime is 684639533. The reversal of 684639523 is 325936486.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-684639523 is a prime.

It is not a weakly prime, because it can be changed into another prime (684639503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342319761 + 342319762.

It is an arithmetic number, because the mean of its divisors is an integer number (342319762).

Almost surely, 2^684639523 is an apocalyptic number.

684639523 is a deficient number, since it is larger than the sum of its proper divisors (1).

684639523 is an equidigital number, since it uses as much as digits as its factorization.

684639523 is an evil number, because the sum of its binary digits is even.

The product of its digits is 933120, while the sum is 46.

The square root of 684639523 is about 26165.6171912684. The cubic root of 684639523 is about 881.3613240448.

The spelling of 684639523 in words is "six hundred eighty-four million, six hundred thirty-nine thousand, five hundred twenty-three".