642249940 has 48 divisors (see below), whose sum is σ = 1413103104. Its totient is φ = 244886400.

The previous prime is 642249929. The next prime is 642249941. The reversal of 642249940 is 49942246.

It is a junction number, because it is equal to n+sod(n) for n = 642249893 and 642249902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642249941) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33810 + ... + 49270.

It is an arithmetic number, because the mean of its divisors is an integer number (29439648).

Almost surely, 2^642249940 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 642249940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (706551552).

642249940 is an abundant number, since it is smaller than the sum of its proper divisors (770853164).

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

642249940 is a wasteful number, since it uses less digits than its factorization.

642249940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15568 (or 15566 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 40.

The square root of 642249940 is about 25342.6506111733. The cubic root of 642249940 is about 862.7825592459.

The spelling of 642249940 in words is "six hundred forty-two million, two hundred forty-nine thousand, nine hundred forty".