661653 has 6 divisors (see below), whose sum is σ = 955734. Its totient is φ = 441096.

The previous prime is 661621. The next prime is 661663. The reversal of 661653 is 356166.

661653 is a `hidden beast` number, since 6 + 6 + 1 + 653 = 666.

It can be written as a sum of positive squares in only one way, i.e., 651249 + 10404 = 807^2 + 102^2 .

It is not a de Polignac number, because 661653 - 2⁵ = 661621 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661603) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36750 + ... + 36767.

It is an arithmetic number, because the mean of its divisors is an integer number (159289).

2⁶⁶¹⁶⁵³ is an apocalyptic number.

It is an amenable number.

661653 is a deficient number, since it is larger than the sum of its proper divisors (294081).

661653 is a wasteful number, since it uses less digits than its factorization.

661653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73523 (or 73520 counting only the distinct ones).

The product of its digits is 3240, while the sum is 27.

The square root of 661653 is about 813.4205554324. The cubic root of 661653 is about 87.1385031290.

The spelling of 661653 in words is "six hundred sixty-one thousand, six hundred fifty-three".