1537661 has 2 divisors, whose sum is σ = 1537662. Its totient is φ = 1537660.

The previous prime is 1537643. The next prime is 1537681. The reversal of 1537661 is 1667351.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1012036 + 525625 = 1006^2 + 725^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1537661 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1537621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 768830 + 768831.

It is an arithmetic number, because the mean of its divisors is an integer number (768831).

2^1537661 is an apocalyptic number.

It is an amenable number.

1537661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1537661 is an equidigital number, since it uses as much as digits as its factorization.

1537661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3780, while the sum is 29.

The square root of 1537661 is about 1240.0245965302. The cubic root of 1537661 is about 115.4215405125.

The spelling of 1537661 in words is "one million, five hundred thirty-seven thousand, six hundred sixty-one".