18911621 has 8 divisors (see below), whose sum is σ = 19282080. Its totient is φ = 18543888.

The previous prime is 18911591. The next prime is 18911623. The reversal of 18911621 is 12611981.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18911621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18911623) 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, 18050 + ... + 19068.

It is an arithmetic number, because the mean of its divisors is an integer number (2410260).

Almost surely, 2^18911621 is an apocalyptic number.

It is an amenable number.

18911621 is a deficient number, since it is larger than the sum of its proper divisors (370459).

18911621 is a wasteful number, since it uses less digits than its factorization.

18911621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1363.

The product of its digits is 864, while the sum is 29.

The square root of 18911621 is about 4348.7493604484. The cubic root of 18911621 is about 266.4257836885.

The spelling of 18911621 in words is "eighteen million, nine hundred eleven thousand, six hundred twenty-one".