1218361638 has 16 divisors (see below), whose sum is σ = 2624163696. Its totient is φ = 374880480.

The previous prime is 1218361607. The next prime is 1218361657. The reversal of 1218361638 is 8361638121.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an alternating number because its digits alternate between odd and even.

It is a junction number, because it is equal to n+sod(n) for n = 1218361596 and 1218361605.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7809933 + ... + 7810088.

It is an arithmetic number, because the mean of its divisors is an integer number (164010231).

Almost surely, 2^1218361638 is an apocalyptic number.

1218361638 is an abundant number, since it is smaller than the sum of its proper divisors (1405802058).

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

1218361638 is a wasteful number, since it uses less digits than its factorization.

1218361638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15620039.

The product of its digits is 41472, while the sum is 39.

The square root of 1218361638 is about 34905.0374301475. The cubic root of 1218361638 is about 1068.0511993438.

Adding to 1218361638 its reverse (8361638121), we get a palindrome (9579999759).

The spelling of 1218361638 in words is "one billion, two hundred eighteen million, three hundred sixty-one thousand, six hundred thirty-eight".