641428640 has 48 divisors (see below), whose sum is σ = 1524200328. Its totient is φ = 255077376.

The previous prime is 641428639. The next prime is 641428661. The reversal of 641428640 is 46824146.

It can be written as a sum of positive squares in 4 ways, for example, as 457446544 + 183982096 = 21388^2 + 13564^2 .

It is a super-2 number, since 2×641428640² = 822861400424499200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 641428640.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16094 + ... + 39266.

Almost surely, 2^641428640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 641428640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (762100164).

641428640 is an abundant number, since it is smaller than the sum of its proper divisors (882771688).

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

641428640 is a wasteful number, since it uses less digits than its factorization.

641428640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23361 (or 23353 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 35.

The square root of 641428640 is about 25326.4415186974. The cubic root of 641428640 is about 862.4146310521.

The spelling of 641428640 in words is "six hundred forty-one million, four hundred twenty-eight thousand, six hundred forty".