1561660 has 24 divisors (see below), whose sum is σ = 3313296. Its totient is φ = 618240.

The previous prime is 1561657. The next prime is 1561673. The reversal of 1561660 is 661651.

It is a nialpdrome in base 11.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1915 + ... + 2605.

It is an arithmetic number, because the mean of its divisors is an integer number (138054).

2^1561660 is an apocalyptic number.

1561660 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1561660 is an abundant number, since it is smaller than the sum of its proper divisors (1751636).

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

1561660 is a wasteful number, since it uses less digits than its factorization.

1561660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 813 (or 811 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 1561660 is about 1249.6639548295. The cubic root of 1561660 is about 116.0189227949.

Subtracting from 1561660 its reverse (661651), we obtain a palindrome (900009).

The spelling of 1561660 in words is "one million, five hundred sixty-one thousand, six hundred sixty".