6661560 has 64 divisors (see below), whose sum is σ = 20465280. Its totient is φ = 1733760.

The previous prime is 6661553. The next prime is 6661583. The reversal of 6661560 is 651666.

It is a Cunningham number, because it is equal to 2581²-1.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4515 + ... + 5805.

It is an arithmetic number, because the mean of its divisors is an integer number (319770).

Almost surely, 2^6661560 is an apocalyptic number.

6661560 is a gapful number since it is divisible by the number (60) 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 6661560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10232640).

6661560 is an abundant number, since it is smaller than the sum of its proper divisors (13803720).

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

6661560 is a wasteful number, since it uses less digits than its factorization.

6661560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1348 (or 1344 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 30.

The square root of 6661560 is about 2580.9998062766. Note that the first 3 decimals coincide. The cubic root of 6661560 is about 188.1591379276.

The spelling of 6661560 in words is "six million, six hundred sixty-one thousand, five hundred sixty".