661617 has 24 divisors (see below), whose sum is σ = 1074528. Its totient is φ = 388800.

The previous prime is 661613. The next prime is 661621. The reversal of 661617 is 716166.

It is an interprime number because it is at equal distance from previous prime (661613) and next prime (661621).

It is not a de Polignac number, because 661617 - 2² = 661613 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661613) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3978 + ... + 4140.

It is an arithmetic number, because the mean of its divisors is an integer number (44772).

2⁶⁶¹⁶¹⁷ is an apocalyptic number.

It is an amenable number.

661617 is a deficient number, since it is larger than the sum of its proper divisors (412911).

661617 is a wasteful number, since it uses less digits than its factorization.

661617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221 (or 218 counting only the distinct ones).

The product of its digits is 1512, while the sum is 27.

The square root of 661617 is about 813.3984263570. The cubic root of 661617 is about 87.1369227220.

The spelling of 661617 in words is "six hundred sixty-one thousand, six hundred seventeen".