642660640 has 48 divisors (see below), whose sum is σ = 1530289152. Its totient is φ = 255032064.

The previous prime is 642660631. The next prime is 642660647. The reversal of 642660640 is 46066246.

It is a junction number, because it is equal to n+sod(n) for n = 642660596 and 642660605.

It is not an unprimeable number, because it can be changed into a prime (642660647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4507 + ... + 36133.

It is an arithmetic number, because the mean of its divisors is an integer number (31881024).

Almost surely, 2^642660640 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 642660640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (765144576).

642660640 is an abundant number, since it is smaller than the sum of its proper divisors (887628512).

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

642660640 is a wasteful number, since it uses less digits than its factorization.

642660640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31769 (or 31761 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 34.

The square root of 642660640 is about 25350.7522570830. The cubic root of 642660640 is about 862.9664281059.

The spelling of 642660640 in words is "six hundred forty-two million, six hundred sixty thousand, six hundred forty".