1221052016661 has 16 divisors (see below), whose sum is σ = 1719671162880. Its totient is φ = 769455131760.

The previous prime is 1221052016651. The next prime is 1221052016663. The reversal of 1221052016661 is 1666102501221.

It is not a de Polignac number, because 1221052016661 - 2¹¹ = 1221052014613 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221052016663) 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, 152665671 + ... + 152673668.

It is an arithmetic number, because the mean of its divisors is an integer number (107479447680).

Almost surely, 2^{1221052016661} is an apocalyptic number.

It is an amenable number.

1221052016661 is a deficient number, since it is larger than the sum of its proper divisors (498619146219).

1221052016661 is a wasteful number, since it uses less digits than its factorization.

1221052016661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305339416.

The product of its (nonzero) digits is 8640, while the sum is 33.

Adding to 1221052016661 its reverse (1666102501221), we get a palindrome (2887154517882).

The spelling of 1221052016661 in words is "one trillion, two hundred twenty-one billion, fifty-two million, sixteen thousand, six hundred sixty-one".