642766 has 4 divisors (see below), whose sum is σ = 964152. Its totient is φ = 321382.

The previous prime is 642739. The next prime is 642769. The reversal of 642766 is 667246.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 667246 = 2 ⋅333623.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642769) by changing a digit.

642766 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160690 + ... + 160693.

It is an arithmetic number, because the mean of its divisors is an integer number (241038).

2⁶⁴²⁷⁶⁶ is an apocalyptic number.

642766 is a deficient number, since it is larger than the sum of its proper divisors (321386).

642766 is a wasteful number, since it uses less digits than its factorization.

642766 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321385.

The product of its digits is 12096, while the sum is 31.

The square root of 642766 is about 801.7268861651. The cubic root of 642766 is about 86.3013584759.

The spelling of 642766 in words is "six hundred forty-two thousand, seven hundred sixty-six".