1391661 has 28 divisors (see below), whose sum is σ = 2203488. Its totient is φ = 876744.

The previous prime is 1391653. The next prime is 1391669. The reversal of 1391661 is 1661931.

It is an interprime number because it is at equal distance from previous prime (1391653) and next prime (1391669).

It is not a de Polignac number, because 1391661 - 2³ = 1391653 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1391669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 16726 + ... + 16808.

It is an arithmetic number, because the mean of its divisors is an integer number (78696).

2^1391661 is an apocalyptic number.

It is an amenable number.

1391661 is a deficient number, since it is larger than the sum of its proper divisors (811827).

1391661 is an frugal number, since it uses more digits than its factorization.

1391661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124 (or 109 counting only the distinct ones).

The product of its digits is 972, while the sum is 27.

The square root of 1391661 is about 1179.6868228475. The cubic root of 1391661 is about 111.6463387170.

The spelling of 1391661 in words is "one million, three hundred ninety-one thousand, six hundred sixty-one".