642910686 has 64 divisors (see below), whose sum is σ = 1457844480. Its totient is φ = 187228160.

The previous prime is 642910637. The next prime is 642910687. The reversal of 642910686 is 686019246.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642910687) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 491245 + ... + 492551.

It is an arithmetic number, because the mean of its divisors is an integer number (22778820).

Almost surely, 2^642910686 is an apocalyptic number.

642910686 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 642910686, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (728922240).

642910686 is an abundant number, since it is smaller than the sum of its proper divisors (814933794).

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

642910686 is a wasteful number, since it uses less digits than its factorization.

642910686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1609.

The product of its (nonzero) digits is 124416, while the sum is 42.

The square root of 642910686 is about 25355.6835048870. The cubic root of 642910686 is about 863.0783344065.

The spelling of 642910686 in words is "six hundred forty-two million, nine hundred ten thousand, six hundred eighty-six".