640555542 has 96 divisors (see below), whose sum is σ = 1583861760. Its totient is φ = 185328000.

The previous prime is 640555541. The next prime is 640555609. The reversal of 640555542 is 245555046.

640555542 is a `hidden beast` number, since 64 + 0 + 5 + 55 + 542 = 666.

It is a super-2 number, since 2×640555542² = 820622804773827528, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 640555497 and 640555506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640555541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 484242 + ... + 485562.

It is an arithmetic number, because the mean of its divisors is an integer number (16498560).

Almost surely, 2^640555542 is an apocalyptic number.

640555542 is a gapful number since it is divisible by the number (62) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 640555542, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (791930880).

640555542 is an abundant number, since it is smaller than the sum of its proper divisors (943306218).

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

640555542 is a wasteful number, since it uses less digits than its factorization.

640555542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1450 (or 1447 counting only the distinct ones).

The product of its (nonzero) digits is 120000, while the sum is 36.

The square root of 640555542 is about 25309.1987625053. The cubic root of 640555542 is about 862.0231536821.

The spelling of 640555542 in words is "six hundred forty million, five hundred fifty-five thousand, five hundred forty-two".