561666616551 has 24 divisors (see below), whose sum is σ = 823642179360. Its totient is φ = 368787422016.

The previous prime is 561666616523. The next prime is 561666616579. The reversal of 561666616551 is 155616666165.

561666616551 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (561666616523) and next prime (561666616579).

It is not a de Polignac number, because 561666616551 - 2⁶ = 561666616487 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561666616501) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1550380 + ... + 1878033.

It is an arithmetic number, because the mean of its divisors is an integer number (34318424140).

Almost surely, 2^561666616551 is an apocalyptic number.

561666616551 is a deficient number, since it is larger than the sum of its proper divisors (261975562809).

561666616551 is a wasteful number, since it uses less digits than its factorization.

561666616551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3428695 (or 3428692 counting only the distinct ones).

The product of its digits is 5832000, while the sum is 54.

The spelling of 561666616551 in words is "five hundred sixty-one billion, six hundred sixty-six million, six hundred sixteen thousand, five hundred fifty-one".