687655321 has 8 divisors (see below), whose sum is σ = 745865064. Its totient is φ = 631418880.

The previous prime is 687655247. The next prime is 687655373. The reversal of 687655321 is 123556786.

It can be written as a sum of positive squares in 4 ways, for example, as 72863296 + 614792025 = 8536^2 + 24795^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 687655321 - 2²¹ = 685558169 is a prime.

It is a super-2 number, since 2×687655321² = 945739680999226082, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (687655021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 492600 + ... + 493993.

It is an arithmetic number, because the mean of its divisors is an integer number (93233133).

Almost surely, 2^687655321 is an apocalyptic number.

It is an amenable number.

687655321 is a deficient number, since it is larger than the sum of its proper divisors (58209743).

687655321 is a wasteful number, since it uses less digits than its factorization.

687655321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 986651.

The product of its digits is 302400, while the sum is 43.

The square root of 687655321 is about 26223.1828922425. The cubic root of 687655321 is about 882.6535439461.

The spelling of 687655321 in words is "six hundred eighty-seven million, six hundred fifty-five thousand, three hundred twenty-one".