686387988 has 432 divisors, whose sum is σ = 2342366208. Its totient is φ = 167270400.

The previous prime is 686387963. The next prime is 686388007. The reversal of 686387988 is 889783686.

It is a super-2 number, since 2×686387988² = 942256940141376288, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 22141533 + ... + 22141563.

It is an arithmetic number, because the mean of its divisors is an integer number (5422144).

Almost surely, 2^686387988 is an apocalyptic number.

686387988 is a gapful number since it is divisible by the number (68) 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 686387988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1171183104).

686387988 is an abundant number, since it is smaller than the sum of its proper divisors (1655978220).

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

686387988 is a wasteful number, since it uses less digits than its factorization.

686387988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116 (or 100 counting only the distinct ones).

The product of its digits is 27869184, while the sum is 63.

The square root of 686387988 is about 26199.0073857770. The cubic root of 686387988 is about 882.1109737424.

The spelling of 686387988 in words is "six hundred eighty-six million, three hundred eighty-seven thousand, nine hundred eighty-eight".