642781440 has 288 divisors, whose sum is σ = 2607816960. Its totient is φ = 146866176.

The previous prime is 642781439. The next prime is 642781487. The reversal of 642781440 is 44187246.

642781440 is a `hidden beast` number, since 642 + 7 + 8 + 1 + 4 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

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 = 642781395 and 642781404.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 240592 + ... + 243248.

It is an arithmetic number, because the mean of its divisors is an integer number (9054920).

Almost surely, 2^642781440 is an apocalyptic number.

642781440 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 642781440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1303908480).

642781440 is an abundant number, since it is smaller than the sum of its proper divisors (1965035520).

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

642781440 is a wasteful number, since it uses less digits than its factorization.

642781440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2694 (or 2674 counting only the distinct ones).

The product of its (nonzero) digits is 43008, while the sum is 36.

The square root of 642781440 is about 25353.1347174270. The cubic root of 642781440 is about 863.0204949063.

The spelling of 642781440 in words is "six hundred forty-two million, seven hundred eighty-one thousand, four hundred forty".