1661555 has 16 divisors (see below), whose sum is σ = 2358720. Its totient is φ = 1099392.

The previous prime is 1661549. The next prime is 1661557. The reversal of 1661555 is 5551661.

It is not a de Polignac number, because 1661555 - 2¹² = 1657459 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is not an unprimeable number, because it can be changed into a prime (1661557) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 197 + ... + 1833.

It is an arithmetic number, because the mean of its divisors is an integer number (147420).

2^1661555 is an apocalyptic number.

1661555 is a deficient number, since it is larger than the sum of its proper divisors (697165).

1661555 is a wasteful number, since it uses less digits than its factorization.

1661555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1678.

The product of its digits is 4500, while the sum is 29.

The square root of 1661555 is about 1289.0131884508. The cubic root of 1661555 is about 118.4417750004.

The spelling of 1661555 in words is "one million, six hundred sixty-one thousand, five hundred fifty-five".