687811920 has 80 divisors (see below), whose sum is σ = 2159266560. Its totient is φ = 181089792.

The previous prime is 687811897. The next prime is 687811921. The reversal of 687811920 is 29118786.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687811921) 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, 822 + ... + 37098.

It is an arithmetic number, because the mean of its divisors is an integer number (26990832).

Almost surely, 2^687811920 is an apocalyptic number.

687811920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 687811920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1079633280).

687811920 is an abundant number, since it is smaller than the sum of its proper divisors (1471454640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

687811920 is a wasteful number, since it uses less digits than its factorization.

687811920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36372 (or 36366 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 42.

The square root of 687811920 is about 26226.1686107598. The cubic root of 687811920 is about 882.7205407719.

The spelling of 687811920 in words is "six hundred eighty-seven million, eight hundred eleven thousand, nine hundred twenty".