616551561 has 8 divisors (see below), whose sum is σ = 913409760. Its totient is φ = 411034356.

The previous prime is 616551557. The next prime is 616551569. The reversal of 616551561 is 165155616.

It is not a de Polignac number, because 616551561 - 2² = 616551557 is a prime.

It is not an unprimeable number, because it can be changed into a prime (616551569) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11417595 + ... + 11417648.

It is an arithmetic number, because the mean of its divisors is an integer number (114176220).

Almost surely, 2^616551561 is an apocalyptic number.

It is an amenable number.

616551561 is a deficient number, since it is larger than the sum of its proper divisors (296858199).

616551561 is a wasteful number, since it uses less digits than its factorization.

616551561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22835252 (or 22835246 counting only the distinct ones).

The product of its digits is 27000, while the sum is 36.

The square root of 616551561 is about 24830.4563188033. The cubic root of 616551561 is about 851.1180493724.

Adding to 616551561 its product of digits (27000), we get a square (616578561 = 24831²).

The spelling of 616551561 in words is "six hundred sixteen million, five hundred fifty-one thousand, five hundred sixty-one".