645742 has 4 divisors (see below), whose sum is σ = 968616. Its totient is φ = 322870.

The previous prime is 645739. The next prime is 645751. The reversal of 645742 is 247546.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 645742.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161434 + ... + 161437.

It is an arithmetic number, because the mean of its divisors is an integer number (242154).

2⁶⁴⁵⁷⁴² is an apocalyptic number.

645742 is a deficient number, since it is larger than the sum of its proper divisors (322874).

645742 is a wasteful number, since it uses less digits than its factorization.

645742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322873.

The product of its digits is 6720, while the sum is 28.

The square root of 645742 is about 803.5807364540. The cubic root of 645742 is about 86.4343449134.

The spelling of 645742 in words is "six hundred forty-five thousand, seven hundred forty-two".