1216205101 has 4 divisors (see below), whose sum is σ = 1226968092. Its totient is φ = 1205442112.

The previous prime is 1216205093. The next prime is 1216205117. The reversal of 1216205101 is 1015026121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1015026121 = 131 ⋅7748291.

It can be written as a sum of positive squares in 2 ways, for example, as 34633225 + 1181571876 = 5885^2 + 34374^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216205101 - 2³ = 1216205093 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 (1216205131) 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, 5381326 + ... + 5381551.

It is an arithmetic number, because the mean of its divisors is an integer number (306742023).

Almost surely, 2^1216205101 is an apocalyptic number.

It is an amenable number.

1216205101 is a deficient number, since it is larger than the sum of its proper divisors (10762991).

1216205101 is a wasteful number, since it uses less digits than its factorization.

1216205101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10762990.

The product of its (nonzero) digits is 120, while the sum is 19.

The square root of 1216205101 is about 34874.1322616062. The cubic root of 1216205101 is about 1067.4206661861.

The spelling of 1216205101 in words is "one billion, two hundred sixteen million, two hundred five thousand, one hundred one".