1581949 has 2 divisors, whose sum is σ = 1581950. Its totient is φ = 1581948.

The previous prime is 1581929. The next prime is 1582001. The reversal of 1581949 is 9491851.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1243225 + 338724 = 1115^2 + 582^2 .

It is an emirp because it is prime and its reverse (9491851) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1581949 - 2¹¹ = 1579901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1581919) 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, 790974 + 790975.

It is an arithmetic number, because the mean of its divisors is an integer number (790975).

2^1581949 is an apocalyptic number.

It is an amenable number.

1581949 is a deficient number, since it is larger than the sum of its proper divisors (1).

1581949 is an equidigital number, since it uses as much as digits as its factorization.

1581949 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 37.

The square root of 1581949 is about 1257.7555406358. The cubic root of 1581949 is about 116.5191996208.

It can be divided in two parts, 158194 and 9, that added together give a triangular number (158203 = T₅₆₂).

The spelling of 1581949 in words is "one million, five hundred eighty-one thousand, nine hundred forty-nine".