687661903 has 2 divisors, whose sum is σ = 687661904. Its totient is φ = 687661902.

The previous prime is 687661901. The next prime is 687661913. The reversal of 687661903 is 309166786.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 687661903 - 2¹ = 687661901 is a prime.

Together with 687661901, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687661901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343830951 + 343830952.

It is an arithmetic number, because the mean of its divisors is an integer number (343830952).

Almost surely, 2^687661903 is an apocalyptic number.

687661903 is a deficient number, since it is larger than the sum of its proper divisors (1).

687661903 is an equidigital number, since it uses as much as digits as its factorization.

687661903 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 326592, while the sum is 46.

The square root of 687661903 is about 26223.3083915817. The cubic root of 687661903 is about 882.6563600891.

The spelling of 687661903 in words is "six hundred eighty-seven million, six hundred sixty-one thousand, nine hundred three".