1216638125 has 10 divisors (see below), whose sum is σ = 1520311782. Its totient is φ = 973310000.

The previous prime is 1216638097. The next prime is 1216638127. The reversal of 1216638125 is 5218366121.

It can be written as a sum of positive squares in 5 ways, for example, as 667860649 + 548777476 = 25843^2 + 23426^2 .

It is not a de Polignac number, because 1216638125 - 2¹⁶ = 1216572589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1216638127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 972686 + ... + 973935.

Almost surely, 2^1216638125 is an apocalyptic number.

It is an amenable number.

1216638125 is a deficient number, since it is larger than the sum of its proper divisors (303673657).

1216638125 is an frugal number, since it uses more digits than its factorization.

1216638125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1946641 (or 1946626 counting only the distinct ones).

The product of its digits is 17280, while the sum is 35.

The square root of 1216638125 is about 34880.3400929521. The cubic root of 1216638125 is about 1067.5473344923.

The spelling of 1216638125 in words is "one billion, two hundred sixteen million, six hundred thirty-eight thousand, one hundred twenty-five".