684921240 has 96 divisors (see below), whose sum is σ = 2229907680. Its totient is φ = 182324736.

The previous prime is 684921227. The next prime is 684921257. The reversal of 684921240 is 42129486.

It is a Cunningham number, because it is equal to 26171²-1.

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 = 684921195 and 684921204.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 260412 + ... + 263028.

It is an arithmetic number, because the mean of its divisors is an integer number (23228205).

Almost surely, 2^684921240 is an apocalyptic number.

684921240 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 684921240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1114953840).

684921240 is an abundant number, since it is smaller than the sum of its proper divisors (1544986440).

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

684921240 is a wasteful number, since it uses less digits than its factorization.

684921240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3361 (or 3354 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The square root of 684921240 is about 26170.9999808949. Note that the first 4 decimals coincide. The cubic root of 684921240 is about 881.4821956428.

The spelling of 684921240 in words is "six hundred eighty-four million, nine hundred twenty-one thousand, two hundred forty".