685421987 has 2 divisors, whose sum is σ = 685421988. Its totient is φ = 685421986.

The previous prime is 685421983. The next prime is 685422013. The reversal of 685421987 is 789124586.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 685421987 - 2² = 685421983 is a prime.

It is not a weakly prime, because it can be changed into another prime (685421983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342710993 + 342710994.

It is an arithmetic number, because the mean of its divisors is an integer number (342710994).

Almost surely, 2^685421987 is an apocalyptic number.

685421987 is a deficient number, since it is larger than the sum of its proper divisors (1).

685421987 is an equidigital number, since it uses as much as digits as its factorization.

685421987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 967680, while the sum is 50.

The square root of 685421987 is about 26180.5650626567. The cubic root of 685421987 is about 881.6969609879.

The spelling of 685421987 in words is "six hundred eighty-five million, four hundred twenty-one thousand, nine hundred eighty-seven".