18649561 has 8 divisors (see below), whose sum is σ = 22567680. Its totient is φ = 15044928.

The previous prime is 18649541. The next prime is 18649571. The reversal of 18649561 is 16594681.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18649561 - 2¹¹ = 18647513 is a prime.

It is a super-2 number, since 2×18649561² = 695612250985442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18649541) 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, 78241 + ... + 78478.

It is an arithmetic number, because the mean of its divisors is an integer number (2820960).

Almost surely, 2^18649561 is an apocalyptic number.

It is an amenable number.

18649561 is a deficient number, since it is larger than the sum of its proper divisors (3918119).

18649561 is a wasteful number, since it uses less digits than its factorization.

18649561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156743.

The product of its digits is 51840, while the sum is 40.

The square root of 18649561 is about 4318.5137489650. The cubic root of 18649561 is about 265.1894266839.

The spelling of 18649561 in words is "eighteen million, six hundred forty-nine thousand, five hundred sixty-one".