687104021 has 2 divisors, whose sum is σ = 687104022. Its totient is φ = 687104020.

The previous prime is 687104017. The next prime is 687104027. The reversal of 687104021 is 120401786.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 565773796 + 121330225 = 23786^2 + 11015^2 .

It is a cyclic number.

It is not a de Polignac number, because 687104021 - 2² = 687104017 is a prime.

It is a super-2 number, since 2×687104021² = 944223871348736882, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (687104027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343552010 + 343552011.

It is an arithmetic number, because the mean of its divisors is an integer number (343552011).

Almost surely, 2^687104021 is an apocalyptic number.

It is an amenable number.

687104021 is a deficient number, since it is larger than the sum of its proper divisors (1).

687104021 is an equidigital number, since it uses as much as digits as its factorization.

687104021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 687104021 is about 26212.6690933983. The cubic root of 687104021 is about 882.4176035551.

The spelling of 687104021 in words is "six hundred eighty-seven million, one hundred four thousand, twenty-one".