18211661 has 8 divisors (see below), whose sum is σ = 20069280. Its totient is φ = 16419312.

The previous prime is 18211643. The next prime is 18211679. The reversal of 18211661 is 16611281.

It is an interprime number because it is at equal distance from previous prime (18211643) and next prime (18211679).

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

It is a de Polignac number, because none of the positive numbers 2^k-18211661 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 18211661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18216661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15731 + ... + 16848.

It is an arithmetic number, because the mean of its divisors is an integer number (2508660).

Almost surely, 2^18211661 is an apocalyptic number.

It is an amenable number.

18211661 is a deficient number, since it is larger than the sum of its proper divisors (1857619).

18211661 is a wasteful number, since it uses less digits than its factorization.

18211661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32635.

The product of its digits is 576, while the sum is 26.

The square root of 18211661 is about 4267.5122729759. The cubic root of 18211661 is about 263.0973775221.

The spelling of 18211661 in words is "eighteen million, two hundred eleven thousand, six hundred sixty-one".