687685401 has 24 divisors (see below), whose sum is σ = 1071490056. Its totient is φ = 422496000.

The previous prime is 687685363. The next prime is 687685409. The reversal of 687685401 is 104586786.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 9603801 + 678081600 = 3099^2 + 26040^2 .

It is not a de Polignac number, because 687685401 - 2¹⁸ = 687423257 is a prime.

It is a super-2 number, since 2×687685401² = 945822421497061602, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (687685409) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 71901 + ... + 80901.

It is an arithmetic number, because the mean of its divisors is an integer number (44645419).

Almost surely, 2^687685401 is an apocalyptic number.

It is an amenable number.

687685401 is a deficient number, since it is larger than the sum of its proper divisors (383804655).

687685401 is a wasteful number, since it uses less digits than its factorization.

687685401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9673 (or 9670 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 45.

The square root of 687685401 is about 26223.7564242806. The cubic root of 687685401 is about 882.6664136841. Note that the first 3 decimals are identical.

The spelling of 687685401 in words is "six hundred eighty-seven million, six hundred eighty-five thousand, four hundred one".