1218161988 has 144 divisors (see below), whose sum is σ = 3307100160. Its totient is φ = 377395200.

The previous prime is 1218161939. The next prime is 1218161993. The reversal of 1218161988 is 8891618121.

1218161988 is a `hidden beast` number, since 1 + 21 + 8 + 1 + 619 + 8 + 8 = 666.

It is a super-2 number, since 2×1218161988² = 2967837258016224288, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3614556 + ... + 3614892.

Almost surely, 2^1218161988 is an apocalyptic number.

1218161988 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1218161988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1653550080).

1218161988 is an abundant number, since it is smaller than the sum of its proper divisors (2088938172).

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

1218161988 is a wasteful number, since it uses less digits than its factorization.

1218161988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 498 (or 493 counting only the distinct ones).

The product of its digits is 55296, while the sum is 45.

The square root of 1218161988 is about 34902.1774105857. The cubic root of 1218161988 is about 1067.9928564939.

The spelling of 1218161988 in words is "one billion, two hundred eighteen million, one hundred sixty-one thousand, nine hundred eighty-eight".