642986 has 8 divisors (see below), whose sum is σ = 990660. Its totient is φ = 312768.

The previous prime is 642977. The next prime is 642997. The reversal of 642986 is 689246.

It can be written as a sum of positive squares in 2 ways, for example, as 516961 + 126025 = 719^2 + 355^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4271 + ... + 4418.

2⁶⁴²⁹⁸⁶ is an apocalyptic number.

642986 is a deficient number, since it is larger than the sum of its proper divisors (347674).

642986 is a wasteful number, since it uses less digits than its factorization.

642986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8728.

The product of its digits is 20736, while the sum is 35.

The square root of 642986 is about 801.8640782577. The cubic root of 642986 is about 86.3112034963.

The spelling of 642986 in words is "six hundred forty-two thousand, nine hundred eighty-six".