661504 has 48 divisors (see below), whose sum is σ = 1474200. Its totient is φ = 294912.

The previous prime is 661483. The next prime is 661513. The reversal of 661504 is 405166.

It is a congruent number.

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, 34807 + ... + 34825.

2⁶⁶¹⁵⁰⁴ is an apocalyptic number.

661504 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (737100).

661504 is an abundant number, since it is smaller than the sum of its proper divisors (812696).

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

661504 is a wasteful number, since it uses less digits than its factorization.

661504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58 (or 38 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 661504 is about 813.3289617369. The cubic root of 661504 is about 87.1319616278.

The spelling of 661504 in words is "six hundred sixty-one thousand, five hundred four".