687221001 has 6 divisors (see below), whose sum is σ = 992652570. Its totient is φ = 458147328.

The previous prime is 687220997. The next prime is 687221009. The reversal of 687221001 is 100122786.

It can be written as a sum of positive squares in only one way, i.e., 668739600 + 18481401 = 25860^2 + 4299^2 .

It is not a de Polignac number, because 687221001 - 2² = 687220997 is a prime.

It is not an unprimeable number, because it can be changed into a prime (687221009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 38178936 + ... + 38178953.

It is an arithmetic number, because the mean of its divisors is an integer number (165442095).

Almost surely, 2^687221001 is an apocalyptic number.

It is an amenable number.

687221001 is a deficient number, since it is larger than the sum of its proper divisors (305431569).

687221001 is a wasteful number, since it uses less digits than its factorization.

687221001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76357895 (or 76357892 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 687221001 is about 26214.9003621986. The cubic root of 687221001 is about 882.4676781438.

Adding to 687221001 its reverse (100122786), we get a palindrome (787343787).

The spelling of 687221001 in words is "six hundred eighty-seven million, two hundred twenty-one thousand, one".