1218638281 has 9 divisors (see below), whose sum is σ = 1417883949. Its totient is φ = 1044337644.

The previous prime is 1218638263. The next prime is 1218638293. The reversal of 1218638281 is 1828368121.

The square root of 1218638281 is 34909.

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

It is not a de Polignac number, because 1218638281 - 2¹¹ = 1218636233 is a prime.

It is a super-2 number, since 2×1218638281² = 2970158519837269922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1218638221) 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, 241870 + ... + 246856.

It is an arithmetic number, because the mean of its divisors is an integer number (157542661).

Almost surely, 2^1218638281 is an apocalyptic number.

1218638281 is the 34909-th square number.

1218638281 is the 17455-th centered octagonal number.

It is an amenable number.

1218638281 is a deficient number, since it is larger than the sum of its proper divisors (199245668).

1218638281 is an frugal number, since it uses more digits than its factorization.

1218638281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9988 (or 4994 counting only the distinct ones).

The product of its digits is 36864, while the sum is 40.

The cubic root of 1218638281 is about 1068.1320309892.

Multiplying 1218638281 by its product of digits (36864), we get a square (44923881590784 = 6702528²).

The spelling of 1218638281 in words is "one billion, two hundred eighteen million, six hundred thirty-eight thousand, two hundred eighty-one".