18491861 has 8 divisors (see below), whose sum is σ = 19065984. Its totient is φ = 17923680.

The previous prime is 18491857. The next prime is 18491881. The reversal of 18491861 is 16819481.

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 18491861 - 2² = 18491857 is a prime.

It is a super-3 number, since 3×18491861³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18491881) 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, 5300 + ... + 8066.

It is an arithmetic number, because the mean of its divisors is an integer number (2383248).

Almost surely, 2^18491861 is an apocalyptic number.

It is an amenable number.

18491861 is a deficient number, since it is larger than the sum of its proper divisors (574123).

18491861 is a wasteful number, since it uses less digits than its factorization.

18491861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2971.

The product of its digits is 13824, while the sum is 38.

The square root of 18491861 is about 4300.2163899041. The cubic root of 18491861 is about 264.4398325127.

The spelling of 18491861 in words is "eighteen million, four hundred ninety-one thousand, eight hundred sixty-one".