1216605101 has 4 divisors (see below), whose sum is σ = 1216775292. Its totient is φ = 1216434912.

The previous prime is 1216605083. The next prime is 1216605113. The reversal of 1216605101 is 1015066121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1015066121 = 263 ⋅3859567.

It can be written as a sum of positive squares in 2 ways, for example, as 812193001 + 404412100 = 28499^2 + 20110^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216605101 - 2¹⁸ = 1216342957 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 (1216601101) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 73880 + ... + 88833.

It is an arithmetic number, because the mean of its divisors is an integer number (304193823).

Almost surely, 2^1216605101 is an apocalyptic number.

It is an amenable number.

1216605101 is a deficient number, since it is larger than the sum of its proper divisors (170191).

1216605101 is an equidigital number, since it uses as much as digits as its factorization.

1216605101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170190.

The product of its (nonzero) digits is 360, while the sum is 23.

The square root of 1216605101 is about 34879.8666998600. The cubic root of 1216605101 is about 1067.5376753610.

The spelling of 1216605101 in words is "one billion, two hundred sixteen million, six hundred five thousand, one hundred one".