661400 has 24 divisors (see below), whose sum is σ = 1538220. Its totient is φ = 264480.

The previous prime is 661393. The next prime is 661417. The reversal of 661400 is 4166.

It is a congruent number.

It is an unprimeable number.

661400 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 5 ways as a sum of consecutive naturals, for example, 1454 + ... + 1853.

2⁶⁶¹⁴⁰⁰ is an apocalyptic number.

It is an amenable number.

661400 is an abundant number, since it is smaller than the sum of its proper divisors (876820).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661400 is a wasteful number, since it uses less digits than its factorization.

661400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3323 (or 3314 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 661400 is about 813.2650244539. The cubic root of 661400 is about 87.1273951656.

Adding to 661400 its reverse (4166), we get a palindrome (665566).

The spelling of 661400 in words is "six hundred sixty-one thousand, four hundred".