642745 has 4 divisors (see below), whose sum is σ = 771300. Its totient is φ = 514192.

The previous prime is 642739. The next prime is 642769. The reversal of 642745 is 547246.

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

It can be written as a sum of positive squares in 2 ways, for example, as 69696 + 573049 = 264^2 + 757^2 .

It is a cyclic number.

It is not a de Polignac number, because 642745 - 2³ = 642737 is a prime.

It is a super-2 number, since 2×642745² = 826242270050, which contains 22 as substring.

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, 64270 + ... + 64279.

It is an arithmetic number, because the mean of its divisors is an integer number (192825).

2⁶⁴²⁷⁴⁵ is an apocalyptic number.

It is an amenable number.

642745 is a deficient number, since it is larger than the sum of its proper divisors (128555).

642745 is a wasteful number, since it uses less digits than its factorization.

642745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128554.

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

The square root of 642745 is about 801.7137893288. The cubic root of 642745 is about 86.3004186065.

It can be divided in two parts, 64 and 2745, that added together give a square (2809 = 53²).

The spelling of 642745 in words is "six hundred forty-two thousand, seven hundred forty-five".