216561242779 has 16 divisors (see below), whose sum is σ = 251049494016. Its totient is φ = 182962080000.

The previous prime is 216561242747. The next prime is 216561242813. The reversal of 216561242779 is 977242165612.

It is not a de Polignac number, because 216561242779 - 2⁵ = 216561242747 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216561243779) 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, 1934044 + ... + 2042950.

It is an arithmetic number, because the mean of its divisors is an integer number (15690593376).

Almost surely, 2^216561242779 is an apocalyptic number.

216561242779 is a deficient number, since it is larger than the sum of its proper divisors (34488251237).

216561242779 is a wasteful number, since it uses less digits than its factorization.

216561242779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112986.

The product of its digits is 2540160, while the sum is 52.

The spelling of 216561242779 in words is "two hundred sixteen billion, five hundred sixty-one million, two hundred forty-two thousand, seven hundred seventy-nine".