642649 has 4 divisors (see below), whose sum is σ = 734464. Its totient is φ = 550836.

The previous prime is 642623. The next prime is 642673. The reversal of 642649 is 946246.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 642649 - 2¹⁹ = 118361 is a prime.

It is an Ulam number.

It is a d-powerful number, because it can be written as 6⁷ + 4⁷ + 6⁷ + 2⁷ + 4⁸ + 9³ .

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 642649.

It is not an unprimeable number, because it can be changed into a prime (642049) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45897 + ... + 45910.

It is an arithmetic number, because the mean of its divisors is an integer number (183616).

2⁶⁴²⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

642649 is a deficient number, since it is larger than the sum of its proper divisors (91815).

642649 is an equidigital number, since it uses as much as digits as its factorization.

642649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91814.

The product of its digits is 10368, while the sum is 31.

The square root of 642649 is about 801.6539153525. The cubic root of 642649 is about 86.2961218000.

The spelling of 642649 in words is "six hundred forty-two thousand, six hundred forty-nine".