18565961 has 4 divisors (see below), whose sum is σ = 18575232. Its totient is φ = 18556692.

The previous prime is 18565957. The next prime is 18565969. The reversal of 18565961 is 16956581.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 16956581 = 103 ⋅164627.

It is a cyclic number.

It is not a de Polignac number, because 18565961 - 2² = 18565957 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18565969) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 245 + ... + 6098.

It is an arithmetic number, because the mean of its divisors is an integer number (4643808).

Almost surely, 2^18565961 is an apocalyptic number.

It is an amenable number.

18565961 is a deficient number, since it is larger than the sum of its proper divisors (9271).

18565961 is an equidigital number, since it uses as much as digits as its factorization.

18565961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9270.

The product of its digits is 64800, while the sum is 41.

The square root of 18565961 is about 4308.8236213612. The cubic root of 18565961 is about 264.7925800670.

The spelling of 18565961 in words is "eighteen million, five hundred sixty-five thousand, nine hundred sixty-one".