1549991749 has 2 divisors, whose sum is σ = 1549991750. Its totient is φ = 1549991748.

The previous prime is 1549991743. The next prime is 1549991759. The reversal of 1549991749 is 9471999451.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1499083524 + 50908225 = 38718^2 + 7135^2 .

It is a cyclic number.

It is not a de Polignac number, because 1549991749 - 2⁹ = 1549991237 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1549991693 and 1549991702.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1549991743) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 774995874 + 774995875.

It is an arithmetic number, because the mean of its divisors is an integer number (774995875).

Almost surely, 2^1549991749 is an apocalyptic number.

It is an amenable number.

1549991749 is a deficient number, since it is larger than the sum of its proper divisors (1).

1549991749 is an equidigital number, since it uses as much as digits as its factorization.

1549991749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3674160, while the sum is 58.

The square root of 1549991749 is about 39369.9345821148. The cubic root of 1549991749 is about 1157.2924737459.

The spelling of 1549991749 in words is "one billion, five hundred forty-nine million, nine hundred ninety-one thousand, seven hundred forty-nine".