661898 has 8 divisors (see below), whose sum is σ = 999108. Its totient is φ = 328864.

The previous prime is 661897. The next prime is 661909. The reversal of 661898 is 898166.

It can be written as a sum of positive squares in 2 ways, for example, as 537289 + 124609 = 733^2 + 353^2 .

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (661897) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 611 + ... + 1302.

2⁶⁶¹⁸⁹⁸ is an apocalyptic number.

661898 is a deficient number, since it is larger than the sum of its proper divisors (337210).

661898 is a wasteful number, since it uses less digits than its factorization.

661898 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2088.

The product of its digits is 20736, while the sum is 38.

The square root of 661898 is about 813.5711400978. The cubic root of 661898 is about 87.1492571540.

The spelling of 661898 in words is "six hundred sixty-one thousand, eight hundred ninety-eight".