685218135420 has 864 divisors, whose sum is σ = 2772449648640. Its totient is φ = 139881530880.

The previous prime is 685218135401. The next prime is 685218135461. The reversal of 685218135420 is 24531812586.

685218135420 is a `hidden beast` number, since 6 + 8 + 5 + 21 + 81 + 3 + 542 + 0 = 666.

It is a super-2 number, since 2×685218135420² (a number of 24 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 138621469 + ... + 138626411.

It is an arithmetic number, because the mean of its divisors is an integer number (3208853760).

Almost surely, 2^685218135420 is an apocalyptic number.

685218135420 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 685218135420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1386224824320).

685218135420 is an abundant number, since it is smaller than the sum of its proper divisors (2087231513220).

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

685218135420 is a wasteful number, since it uses less digits than its factorization.

685218135420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5032 (or 5004 counting only the distinct ones).

The product of its (nonzero) digits is 460800, while the sum is 45.

The spelling of 685218135420 in words is "six hundred eighty-five billion, two hundred eighteen million, one hundred thirty-five thousand, four hundred twenty".