1220661252561 has 16 divisors (see below), whose sum is σ = 1637385235200. Its totient is φ = 808863675648.

The previous prime is 1220661252553. The next prime is 1220661252623. The reversal of 1220661252561 is 1652521660221.

It is not a de Polignac number, because 1220661252561 - 2³ = 1220661252553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1220661252061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 379896 + ... + 1607993.

It is an arithmetic number, because the mean of its divisors is an integer number (102336577200).

Almost surely, 2^{1220661252561} is an apocalyptic number.

It is an amenable number.

1220661252561 is a deficient number, since it is larger than the sum of its proper divisors (416723982639).

1220661252561 is a wasteful number, since it uses less digits than its factorization.

1220661252561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1989128.

The product of its (nonzero) digits is 86400, while the sum is 39.

The spelling of 1220661252561 in words is "one trillion, two hundred twenty billion, six hundred sixty-one million, two hundred fifty-two thousand, five hundred sixty-one".