1212016661 has 4 divisors (see below), whose sum is σ = 1212148524. Its totient is φ = 1211884800.

The previous prime is 1212016651. The next prime is 1212016679. The reversal of 1212016661 is 1666102121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1666102121 = 59 ⋅28239019.

It can be written as a sum of positive squares in 2 ways, for example, as 296046436 + 915970225 = 17206^2 + 30265^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1212016661 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1212016661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1212016601) 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, 51020 + ... + 70901.

It is an arithmetic number, because the mean of its divisors is an integer number (303037131).

Almost surely, 2^1212016661 is an apocalyptic number.

It is an amenable number.

1212016661 is a deficient number, since it is larger than the sum of its proper divisors (131863).

1212016661 is an equidigital number, since it uses as much as digits as its factorization.

1212016661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 131862.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 1212016661 is about 34814.0296575964. The cubic root of 1212016661 is about 1066.1939077622.

Adding to 1212016661 its reverse (1666102121), we get a palindrome (2878118782).

The spelling of 1212016661 in words is "one billion, two hundred twelve million, sixteen thousand, six hundred sixty-one".