661984 has 24 divisors (see below), whose sum is σ = 1321488. Its totient is φ = 326400.

The previous prime is 661961. The next prime is 661987. The reversal of 661984 is 489166.

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661987) by changing a digit.

661984 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4309 + ... + 4459.

It is an arithmetic number, because the mean of its divisors is an integer number (55062).

2⁶⁶¹⁹⁸⁴ is an apocalyptic number.

It is an amenable number.

661984 is a deficient number, since it is larger than the sum of its proper divisors (659504).

661984 is a wasteful number, since it uses less digits than its factorization.

661984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 298 (or 290 counting only the distinct ones).

The product of its digits is 10368, while the sum is 34.

The square root of 661984 is about 813.6239917800. The cubic root of 661984 is about 87.1530314070.

The spelling of 661984 in words is "six hundred sixty-one thousand, nine hundred eighty-four".