18633631255561 has 27 divisors (see below), whose sum is σ = 21802673892807. Its totient is φ = 15878780583120.

The previous prime is 18633631255559. The next prime is 18633631255583. The reversal of 18633631255561 is 16555213633681.

The square root of 18633631255561 is 4316669.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 205327703161 + 18428303552400 = 453131^2 + 4292820^2 .

It is not a de Polignac number, because 18633631255561 - 2¹ = 18633631255559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18633631205561) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 5469217920 + ... + 5469221326.

Almost surely, 2^{18633631255561} is an apocalyptic number.

18633631255561 is the 4316669-th square number.

18633631255561 is the 2158335-th centered octagonal number.

It is an amenable number.

18633631255561 is a deficient number, since it is larger than the sum of its proper divisors (3169042637246).

18633631255561 is an frugal number, since it uses more digits than its factorization.

18633631255561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7190 (or 3595 counting only the distinct ones).

The product of its digits is 11664000, while the sum is 55.

The spelling of 18633631255561 in words is "eighteen trillion, six hundred thirty-three billion, six hundred thirty-one million, two hundred fifty-five thousand, five hundred sixty-one".