1661571 has 12 divisors (see below), whose sum is σ = 2411448. Its totient is φ = 1102464.

The previous prime is 1661567. The next prime is 1661587. The reversal of 1661571 is 1751661.

It is not a de Polignac number, because 1661571 - 2² = 1661567 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (1662571) 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, 2916 + ... + 3438.

It is an arithmetic number, because the mean of its divisors is an integer number (200954).

2^1661571 is an apocalyptic number.

1661571 is a deficient number, since it is larger than the sum of its proper divisors (749877).

1661571 is a wasteful number, since it uses less digits than its factorization.

1661571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 882 (or 879 counting only the distinct ones).

The product of its digits is 1260, while the sum is 27.

The square root of 1661571 is about 1289.0193947338. The cubic root of 1661571 is about 118.4421551789.

The spelling of 1661571 in words is "one million, six hundred sixty-one thousand, five hundred seventy-one".