648781 has 4 divisors (see below), whose sum is σ = 741472. Its totient is φ = 556092.

The previous prime is 648779. The next prime is 648803. The reversal of 648781 is 187846.

648781 = T₂₃₈ + T₂₃₉ + ... + T₂₅₈.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 187846 = 2 ⋅93923.

It is a cyclic number.

It is not a de Polignac number, because 648781 - 2¹ = 648779 is a prime.

It is a super-2 number, since 2×648781² = 841833571922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (648731) 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, 46335 + ... + 46348.

It is an arithmetic number, because the mean of its divisors is an integer number (185368).

2⁶⁴⁸⁷⁸¹ is an apocalyptic number.

It is an amenable number.

648781 is a deficient number, since it is larger than the sum of its proper divisors (92691).

648781 is an equidigital number, since it uses as much as digits as its factorization.

648781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92690.

The product of its digits is 10752, while the sum is 34.

The square root of 648781 is about 805.4694283460. The cubic root of 648781 is about 86.5697255977.

The spelling of 648781 in words is "six hundred forty-eight thousand, seven hundred eighty-one".