642640000 has 160 divisors (see below), whose sum is σ = 1660952700. Its totient is φ = 247296000.

The previous prime is 642639961. The next prime is 642640003. The reversal of 642640000 is 46246.

It can be written as a sum of positive squares in 10 ways, for example, as 121705024 + 520934976 = 11032^2 + 22824^2 .

It is a tau number, because it is divible by the number of its divisors (160).

It is not an unprimeable number, because it can be changed into a prime (642640003) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2319862 + ... + 2320138.

Almost surely, 2^642640000 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 642640000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (830476350).

642640000 is an abundant number, since it is smaller than the sum of its proper divisors (1018312700).

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

642640000 is an equidigital number, since it uses as much as digits as its factorization.

642640000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340 (or 313 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 22.

The square root of 642640000 is about 25350.3451653030. The cubic root of 642640000 is about 862.9571895246.

Adding to 642640000 its reverse (46246), we get a palindrome (642686246).

The spelling of 642640000 in words is "six hundred forty-two million, six hundred forty thousand".