1216638738 has 48 divisors (see below), whose sum is σ = 3145059360. Its totient is φ = 347610312.

The previous prime is 1216638733. The next prime is 1216638739. The reversal of 1216638738 is 8378366121.

1216638738 is a `hidden beast` number, since 1 + 2 + 1 + 6 + 638 + 7 + 3 + 8 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 1216638693 and 1216638702.

It is not an unprimeable number, because it can be changed into a prime (1216638733) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 227256 + ... + 232547.

It is an arithmetic number, because the mean of its divisors is an integer number (65522070).

Almost surely, 2^1216638738 is an apocalyptic number.

1216638738 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1216638738 is an abundant number, since it is smaller than the sum of its proper divisors (1928420622).

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

1216638738 is a wasteful number, since it uses less digits than its factorization.

1216638738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 459828 (or 459815 counting only the distinct ones).

The product of its digits is 290304, while the sum is 45.

The square root of 1216638738 is about 34880.3488801359. The cubic root of 1216638738 is about 1067.5475137859.

The spelling of 1216638738 in words is "one billion, two hundred sixteen million, six hundred thirty-eight thousand, seven hundred thirty-eight".