1491661 has 2 divisors, whose sum is σ = 1491662. Its totient is φ = 1491660.

The previous prime is 1491653. The next prime is 1491667. The reversal of 1491661 is 1661941.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1010025 + 481636 = 1005^2 + 694^2 .

It is a cyclic number.

It is not a de Polignac number, because 1491661 - 2³ = 1491653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1491667) 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 as a sum of consecutive naturals, namely, 745830 + 745831.

It is an arithmetic number, because the mean of its divisors is an integer number (745831).

2^1491661 is an apocalyptic number.

It is an amenable number.

1491661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1491661 is an equidigital number, since it uses as much as digits as its factorization.

1491661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296, while the sum is 28.

The square root of 1491661 is about 1221.3357441752. The cubic root of 1491661 is about 114.2589016713.

The spelling of 1491661 in words is "one million, four hundred ninety-one thousand, six hundred sixty-one".