640155428640 has 1344 divisors, whose sum is σ = 2860797284352. Its totient is φ = 131681894400.

The previous prime is 640155428623. The next prime is 640155428659. The reversal of 640155428640 is 46824551046.

It is a happy number.

640155428640 is a `hidden beast` number, since 6 + 40 + 1 + 5 + 542 + 8 + 64 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 223 ways as a sum of consecutive naturals, for example, 435183105 + ... + 435184575.

It is an arithmetic number, because the mean of its divisors is an integer number (2128569408).

Almost surely, 2^640155428640 is an apocalyptic number.

640155428640 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 640155428640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1430398642176).

640155428640 is an abundant number, since it is smaller than the sum of its proper divisors (2220641855712).

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

640155428640 is a wasteful number, since it uses less digits than its factorization.

640155428640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1565 (or 1542 counting only the distinct ones).

The product of its (nonzero) digits is 921600, while the sum is 45.

Adding to 640155428640 its reverse (46824551046), we get a palindrome (686979979686).

The spelling of 640155428640 in words is "six hundred forty billion, one hundred fifty-five million, four hundred twenty-eight thousand, six hundred forty".