687531761 has 4 divisors (see below), whose sum is σ = 785750592. Its totient is φ = 589312932.

The previous prime is 687531751. The next prime is 687531763. The reversal of 687531761 is 167135786.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 167135786 = 2 ⋅83567893.

It is a cyclic number.

It is not a de Polignac number, because 687531761 - 2¹⁸ = 687269617 is a prime.

It is a super-2 number, since 2×687531761² = 945399844767522242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (687531763) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 49109405 + ... + 49109418.

It is an arithmetic number, because the mean of its divisors is an integer number (196437648).

Almost surely, 2^687531761 is an apocalyptic number.

It is an amenable number.

687531761 is a deficient number, since it is larger than the sum of its proper divisors (98218831).

687531761 is an equidigital number, since it uses as much as digits as its factorization.

687531761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98218830.

The product of its digits is 211680, while the sum is 44.

The square root of 687531761 is about 26220.8268557649. The cubic root of 687531761 is about 882.6006748214.

The spelling of 687531761 in words is "six hundred eighty-seven million, five hundred thirty-one thousand, seven hundred sixty-one".