648661 has 8 divisors (see below), whose sum is σ = 716184. Its totient is φ = 583680.

The previous prime is 648653. The next prime is 648671. The reversal of 648661 is 166846.

648661 = 569² + 570².

It can be written as a sum of positive squares in 4 ways, for example, as 18225 + 630436 = 135^2 + 794^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 6-Lehmer number, since φ(648661) divides (648661-1)⁶.

It is a cyclic number.

It is not a de Polignac number, because 648661 - 2³ = 648653 is a prime.

It is a super-2 number, since 2×648661² = 841522185842, 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 (648631) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76 + ... + 1141.

It is an arithmetic number, because the mean of its divisors is an integer number (89523).

2⁶⁴⁸⁶⁶¹ is an apocalyptic number.

648661 is the 570-th centered square number.

It is an amenable number.

648661 is a deficient number, since it is larger than the sum of its proper divisors (67523).

648661 is a wasteful number, since it uses less digits than its factorization.

648661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1271.

The product of its digits is 6912, while the sum is 31.

The square root of 648661 is about 805.3949341783. The cubic root of 648661 is about 86.5643878912.

The spelling of 648661 in words is "six hundred forty-eight thousand, six hundred sixty-one".