661554 has 16 divisors (see below), whose sum is σ = 1470240. Its totient is φ = 220500.

The previous prime is 661553. The next prime is 661603. The reversal of 661554 is 455166.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (661553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6072 + ... + 6179.

It is an arithmetic number, because the mean of its divisors is an integer number (91890).

2⁶⁶¹⁵⁵⁴ is an apocalyptic number.

661554 is an abundant number, since it is smaller than the sum of its proper divisors (808686).

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

661554 is a wasteful number, since it uses less digits than its factorization.

661554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12262 (or 12256 counting only the distinct ones).

The product of its digits is 3600, while the sum is 27.

The square root of 661554 is about 813.3596990262. The cubic root of 661554 is about 87.1341568719.

The spelling of 661554 in words is "six hundred sixty-one thousand, five hundred fifty-four".