18361197561 has 16 divisors (see below), whose sum is σ = 29451545600. Its totient is φ = 9939896208.

The previous prime is 18361197541. The next prime is 18361197581. The reversal of 18361197561 is 16579116381.

It is an interprime number because it is at equal distance from previous prime (18361197541) and next prime (18361197581).

It is not a de Polignac number, because 18361197561 - 2¹⁵ = 18361164793 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18361197561.

It is not an unprimeable number, because it can be changed into a prime (18361197541) 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, 23008621 + ... + 23009418.

It is an arithmetic number, because the mean of its divisors is an integer number (1840721600).

Almost surely, 2^18361197561 is an apocalyptic number.

It is an amenable number.

18361197561 is a deficient number, since it is larger than the sum of its proper divisors (11090348039).

18361197561 is a wasteful number, since it uses less digits than its factorization.

18361197561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46018068.

The product of its digits is 272160, while the sum is 48.

The spelling of 18361197561 in words is "eighteen billion, three hundred sixty-one million, one hundred ninety-seven thousand, five hundred sixty-one".