687632781 has 16 divisors (see below), whose sum is σ = 1052835840. Its totient is φ = 394812720.

The previous prime is 687632773. The next prime is 687632797. The reversal of 687632781 is 187236786.

It is not a de Polignac number, because 687632781 - 2³ = 687632773 is a prime.

It is a super-2 number, since 2×687632781² = 945677683011587922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 687632781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687632581) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 547725 + ... + 548978.

It is an arithmetic number, because the mean of its divisors is an integer number (65802240).

Almost surely, 2^687632781 is an apocalyptic number.

It is an amenable number.

687632781 is a deficient number, since it is larger than the sum of its proper divisors (365203059).

687632781 is a wasteful number, since it uses less digits than its factorization.

687632781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1096736.

The product of its digits is 677376, while the sum is 48.

The square root of 687632781 is about 26222.7531163301. The cubic root of 687632781 is about 882.6438999536.

The spelling of 687632781 in words is "six hundred eighty-seven million, six hundred thirty-two thousand, seven hundred eighty-one".