1218517938225 has 81 divisors (see below), whose sum is σ = 2539069232193. Its totient is φ = 556983786240.

The previous prime is 1218517938181. The next prime is 1218517938247. The reversal of 1218517938225 is 5228397158121.

The square root of 1218517938225 is 1103865.

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

1218517938225 is a `hidden beast` number, since 1 + 2 + 18 + 517 + 93 + 8 + 2 + 25 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 763654020129 + 454863918096 = 873873^2 + 674436^2 .

It is not a de Polignac number, because 1218517938225 - 2⁷ = 1218517938097 is a prime.

It is a super-2 number, since 2×1218517938225² (a number of 25 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 115900569 + ... + 115911081.

Almost surely, 2^{1218517938225} is an apocalyptic number.

1218517938225 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1218517938225 is the 1103865-th square number.

1218517938225 is the 551933-rd centered octagonal number.

It is an amenable number.

1218517938225 is an abundant number, since it is smaller than the sum of its proper divisors (1320551293968).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1218517938225 is an frugal number, since it uses more digits than its factorization.

1218517938225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21056 (or 10528 counting only the distinct ones).

The product of its digits is 2419200, while the sum is 54.

The spelling of 1218517938225 in words is "one trillion, two hundred eighteen billion, five hundred seventeen million, nine hundred thirty-eight thousand, two hundred twenty-five".