655681 has 8 divisors (see below), whose sum is σ = 729344. Its totient is φ = 585360.

The previous prime is 655657. The next prime is 655687. The reversal of 655681 is 186556.

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

It is a cyclic number.

It is not a de Polignac number, because 655681 - 2⁵ = 655649 is a prime.

It is a super-2 number, since 2×655681² = 859835147522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (655687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 411 + ... + 1216.

It is an arithmetic number, because the mean of its divisors is an integer number (91168).

2⁶⁵⁵⁶⁸¹ is an apocalyptic number.

It is an amenable number.

655681 is a deficient number, since it is larger than the sum of its proper divisors (73663).

655681 is a wasteful number, since it uses less digits than its factorization.

655681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1671.

The product of its digits is 7200, while the sum is 31.

The square root of 655681 is about 809.7413167179. The cubic root of 655681 is about 86.8755431879.

The spelling of 655681 in words is "six hundred fifty-five thousand, six hundred eighty-one".