1211071665 has 16 divisors (see below), whose sum is σ = 1938319488. Its totient is φ = 645703296.

The previous prime is 1211071657. The next prime is 1211071669. The reversal of 1211071665 is 5661701121.

It is not a de Polignac number, because 1211071665 - 2³ = 1211071657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1211071669) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45789 + ... + 67221.

It is an arithmetic number, because the mean of its divisors is an integer number (121144968).

Almost surely, 2^1211071665 is an apocalyptic number.

1211071665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1211071665 is a deficient number, since it is larger than the sum of its proper divisors (727247823).

1211071665 is a wasteful number, since it uses less digits than its factorization.

1211071665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25208.

The product of its (nonzero) digits is 2520, while the sum is 30.

The square root of 1211071665 is about 34800.4549539227. The cubic root of 1211071665 is about 1065.9167358437.

Adding to 1211071665 its reverse (5661701121), we get a palindrome (6872772786).

The spelling of 1211071665 in words is "one billion, two hundred eleven million, seventy-one thousand, six hundred sixty-five".