684881687 has 4 divisors (see below), whose sum is σ = 782721936. Its totient is φ = 587041440.

The previous prime is 684881677. The next prime is 684881689. The reversal of 684881687 is 786188486.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 786188486 = 2 ⋅393094243.

It is a cyclic number.

It is not a de Polignac number, because 684881687 - 2¹⁸ = 684619543 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684881689) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48920114 + ... + 48920127.

It is an arithmetic number, because the mean of its divisors is an integer number (195680484).

Almost surely, 2^684881687 is an apocalyptic number.

684881687 is a deficient number, since it is larger than the sum of its proper divisors (97840249).

684881687 is an equidigital number, since it uses as much as digits as its factorization.

684881687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97840248.

The product of its digits is 4128768, while the sum is 56.

The square root of 684881687 is about 26170.2443053174. The cubic root of 684881687 is about 881.4652272994.

The spelling of 684881687 in words is "six hundred eighty-four million, eight hundred eighty-one thousand, six hundred eighty-seven".