1555197749 has 4 divisors (see below), whose sum is σ = 1777368864. Its totient is φ = 1333026636.

The previous prime is 1555197733. The next prime is 1555197751. The reversal of 1555197749 is 9477915551.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9477915551 = 13 ⋅729070427.

It is a cyclic number.

It is not a de Polignac number, because 1555197749 - 2⁴ = 1555197733 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1555197749.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1551197749) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111085547 + ... + 111085560.

It is an arithmetic number, because the mean of its divisors is an integer number (444342216).

Almost surely, 2^1555197749 is an apocalyptic number.

It is an amenable number.

1555197749 is a deficient number, since it is larger than the sum of its proper divisors (222171115).

1555197749 is an equidigital number, since it uses as much as digits as its factorization.

1555197749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222171114.

The product of its digits is 1984500, while the sum is 53.

The square root of 1555197749 is about 39435.9956004663. The cubic root of 1555197749 is about 1158.5867025459.

The spelling of 1555197749 in words is "one billion, five hundred fifty-five million, one hundred ninety-seven thousand, seven hundred forty-nine".