661736 has 16 divisors (see below), whose sum is σ = 1250340. Its totient is φ = 328320.

The previous prime is 661721. The next prime is 661741. The reversal of 661736 is 637166.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 649636 + 12100 = 806^2 + 110^2 .

It is a junction number, because it is equal to n+sod(n) for n = 661699 and 661708.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1220 + ... + 1676.

2⁶⁶¹⁷³⁶ is an apocalyptic number.

It is an amenable number.

661736 is a deficient number, since it is larger than the sum of its proper divisors (588604).

661736 is a wasteful number, since it uses less digits than its factorization.

661736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644 (or 640 counting only the distinct ones).

The product of its digits is 4536, while the sum is 29.

The square root of 661736 is about 813.4715729514. The cubic root of 661736 is about 87.1421466266.

The spelling of 661736 in words is "six hundred sixty-one thousand, seven hundred thirty-six".