840637440 has 220 divisors, whose sum is σ = 3013855416. Its totient is φ = 224059392.

The previous prime is 840637439. The next prime is 840637451. The reversal of 840637440 is 44736048.

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 = 840637395 and 840637404.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 413707 + ... + 415733.

Almost surely, 2^840637440 is an apocalyptic number.

840637440 is a gapful number since it is divisible by the number (80) 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 840637440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1506927708).

840637440 is an abundant number, since it is smaller than the sum of its proper divisors (2173217976).

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

840637440 is a wasteful number, since it uses less digits than its factorization.

840637440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2064 (or 2037 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 36.

The square root of 840637440 is about 28993.7482916576. The cubic root of 840637440 is about 943.7774061015. Note that the first 3 decimals are identical.

The spelling of 840637440 in words is "eight hundred forty million, six hundred thirty-seven thousand, four hundred forty".