661550 has 24 divisors (see below), whose sum is σ = 1252152. Its totient is φ = 260000.

The previous prime is 661547. The next prime is 661553. The reversal of 661550 is 55166.

It is an interprime number because it is at equal distance from previous prime (661547) and next prime (661553).

It is a congruent number.

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

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4985 + ... + 5115.

It is an arithmetic number, because the mean of its divisors is an integer number (52173).

2⁶⁶¹⁵⁵⁰ is an apocalyptic number.

661550 is a deficient number, since it is larger than the sum of its proper divisors (590602).

661550 is a wasteful number, since it uses less digits than its factorization.

661550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244 (or 239 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 661550 is about 813.3572400858. The cubic root of 661550 is about 87.1339812564.

The spelling of 661550 in words is "six hundred sixty-one thousand, five hundred fifty".