687461391 has 16 divisors (see below), whose sum is σ = 1043303520. Its totient is φ = 447128640.

The previous prime is 687461387. The next prime is 687461393. The reversal of 687461391 is 193164786.

It is a happy number.

It is not a de Polignac number, because 687461391 - 2² = 687461387 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687461393) 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, 309400 + ... + 311613.

It is an arithmetic number, because the mean of its divisors is an integer number (65206470).

Almost surely, 2^687461391 is an apocalyptic number.

687461391 is a deficient number, since it is larger than the sum of its proper divisors (355842129).

687461391 is a wasteful number, since it uses less digits than its factorization.

687461391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 621063 (or 621057 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 687461391 is about 26219.4849491747. The cubic root of 687461391 is about 882.5705619199.

It can be divided in two parts, 6874 and 61391, that added together give a triangular number (68265 = T₃₆₉).

The spelling of 687461391 in words is "six hundred eighty-seven million, four hundred sixty-one thousand, three hundred ninety-one".