321686640 has 200 divisors, whose sum is σ = 1219105008. Its totient is φ = 77967360.

The previous prime is 321686567. The next prime is 321686681. The reversal of 321686640 is 46686123.

321686640 is a `hidden beast` number, since 3 + 2 + 1 + 6 + 8 + 6 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 321686595 and 321686604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 69024 + ... + 73536.

Almost surely, 2^321686640 is an apocalyptic number.

321686640 is a gapful number since it is divisible by the number (30) 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 321686640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (609552504).

321686640 is an abundant number, since it is smaller than the sum of its proper divisors (897418368).

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

321686640 is a wasteful number, since it uses less digits than its factorization.

321686640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4549 (or 4534 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The square root of 321686640 is about 17935.6248845698. The cubic root of 321686640 is about 685.1899876160.

The spelling of 321686640 in words is "three hundred twenty-one million, six hundred eighty-six thousand, six hundred forty".