1918770728809 has 9 divisors (see below), whose sum is σ = 2109078789181. Its totient is φ = 1744323174220.

The previous prime is 1918770728761. The next prime is 1918770728821. The reversal of 1918770728809 is 9088270778191.

The square root of 1918770728809 is 1385197.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 1918770728809 - 2⁹ = 1918770728297 is a prime.

It is a super-2 number, since 2×1918770728809² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1918770728869) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 15174204 + ... + 15300130.

Almost surely, 2^{1918770728809} is an apocalyptic number.

1918770728809 is the 1385197-th square number.

1918770728809 is the 692599-th centered octagonal number.

It is an amenable number.

1918770728809 is a deficient number, since it is larger than the sum of its proper divisors (190308060372).

1918770728809 is an frugal number, since it uses more digits than its factorization.

1918770728809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251876 (or 125938 counting only the distinct ones).

The product of its (nonzero) digits is 28449792, while the sum is 67.

The spelling of 1918770728809 in words is "one trillion, nine hundred eighteen billion, seven hundred seventy million, seven hundred twenty-eight thousand, eight hundred nine".