687971385 has 24 divisors (see below), whose sum is σ = 1262631240. Its totient is φ = 345334272.

The previous prime is 687971381. The next prime is 687971413. The reversal of 687971385 is 583179786.

It can be written as a sum of positive squares in 4 ways, for example, as 360506169 + 327465216 = 18987^2 + 18096^2 .

It is not a de Polignac number, because 687971385 - 2² = 687971381 is a prime.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (687971381) 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, 448890 + ... + 450419.

It is an arithmetic number, because the mean of its divisors is an integer number (52609635).

Almost surely, 2^687971385 is an apocalyptic number.

It is an amenable number.

687971385 is a deficient number, since it is larger than the sum of its proper divisors (574659855).

687971385 is a wasteful number, since it uses less digits than its factorization.

687971385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 899337 (or 899334 counting only the distinct ones).

The product of its digits is 2540160, while the sum is 54.

The square root of 687971385 is about 26229.2086232124. The cubic root of 687971385 is about 882.7887532924.

The spelling of 687971385 in words is "six hundred eighty-seven million, nine hundred seventy-one thousand, three hundred eighty-five".