685721211840 has 448 divisors, whose sum is σ = 2784867379200. Its totient is φ = 155590336512.

The previous prime is 685721211823. The next prime is 685721211911. The reversal of 685721211840 is 48112127586.

685721211840 is a `hidden beast` number, since 6 + 8 + 572 + 1 + 21 + 18 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (448).

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 pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 8244381 + ... + 8327139.

Almost surely, 2^685721211840 is an apocalyptic number.

685721211840 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 685721211840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1392433689600).

685721211840 is an abundant number, since it is smaller than the sum of its proper divisors (2099146167360).

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

685721211840 is a wasteful number, since it uses less digits than its factorization.

685721211840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82929 (or 82913 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 45.

The spelling of 685721211840 in words is "six hundred eighty-five billion, seven hundred twenty-one million, two hundred eleven thousand, eight hundred forty".