642981686 has 8 divisors (see below), whose sum is σ = 964607664. Its totient is φ = 321445800.

The previous prime is 642981683. The next prime is 642981697. The reversal of 642981686 is 686189246.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642981683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 290 + ... + 35861.

It is an arithmetic number, because the mean of its divisors is an integer number (120575958).

Almost surely, 2^642981686 is an apocalyptic number.

642981686 is a deficient number, since it is larger than the sum of its proper divisors (321625978).

642981686 is a wasteful number, since it uses less digits than its factorization.

642981686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45046.

The product of its digits is 995328, while the sum is 50.

The square root of 642981686 is about 25357.0835468119. The cubic root of 642981686 is about 863.1101046598.

The spelling of 642981686 in words is "six hundred forty-two million, nine hundred eighty-one thousand, six hundred eighty-six".