661544 has 16 divisors (see below), whose sum is σ = 1336020. Its totient is φ = 305280.

The previous prime is 661541. The next prime is 661547. The reversal of 661544 is 445166.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (661541) and next prime (661547).

It can be written as a sum of positive squares in 2 ways, for example, as 592900 + 68644 = 770^2 + 262^2 .

It is a Smith number, since the sum of its digits (26) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is not an unprimeable number, because it can be changed into a prime (661541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3077 + ... + 3284.

2⁶⁶¹⁵⁴⁴ is an apocalyptic number.

It is an amenable number.

661544 is an abundant number, since it is smaller than the sum of its proper divisors (674476).

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

661544 is a wasteful number, since it uses less digits than its factorization.

661544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6380 (or 6376 counting only the distinct ones).

The product of its digits is 2880, while the sum is 26.

The square root of 661544 is about 813.3535516613. The cubic root of 661544 is about 87.1337178319.

The spelling of 661544 in words is "six hundred sixty-one thousand, five hundred forty-four".