642646640 has 40 divisors (see below), whose sum is σ = 1495873008. Its totient is φ = 256762880.

The previous prime is 642646577. The next prime is 642646643. The reversal of 642646640 is 46646246.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 642646594 and 642646603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642646643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 73544 + ... + 81816.

Almost surely, 2^642646640 is an apocalyptic number.

It is an amenable number.

642646640 is an abundant number, since it is smaller than the sum of its proper divisors (853226368).

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

642646640 is a wasteful number, since it uses less digits than its factorization.

642646640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9257 (or 9251 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 38.

The square root of 642646640 is about 25350.4761296509. The cubic root of 642646640 is about 862.9601616479.

The spelling of 642646640 in words is "six hundred forty-two million, six hundred forty-six thousand, six hundred forty".