642439818 has 144 divisors (see below), whose sum is σ = 1583880480. Its totient is φ = 187551936.

The previous prime is 642439807. The next prime is 642439829. The reversal of 642439818 is 818934246.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (642439807) and next prime (642439829).

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 9588621 + ... + 9588687.

It is an arithmetic number, because the mean of its divisors is an integer number (10999170).

Almost surely, 2^642439818 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 642439818, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (791940240).

642439818 is an abundant number, since it is smaller than the sum of its proper divisors (941440662).

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

642439818 is a wasteful number, since it uses less digits than its factorization.

642439818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193 (or 167 counting only the distinct ones).

The product of its digits is 331776, while the sum is 45.

The square root of 642439818 is about 25346.3965486221. The cubic root of 642439818 is about 862.8675766588.

The spelling of 642439818 in words is "six hundred forty-two million, four hundred thirty-nine thousand, eight hundred eighteen".