18857621 has 4 divisors (see below), whose sum is σ = 18956544. Its totient is φ = 18758700.

The previous prime is 18857617. The next prime is 18857623. The reversal of 18857621 is 12675881.

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 an emirpimes, since its reverse is a distinct semiprime: 12675881 = 991 ⋅12791.

It is a cyclic number.

It is not a de Polignac number, because 18857621 - 2² = 18857617 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18857623) 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, 49175 + ... + 49556.

It is an arithmetic number, because the mean of its divisors is an integer number (4739136).

Almost surely, 2^18857621 is an apocalyptic number.

It is an amenable number.

18857621 is a deficient number, since it is larger than the sum of its proper divisors (98923).

18857621 is an equidigital number, since it uses as much as digits as its factorization.

18857621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98922.

The product of its digits is 26880, while the sum is 38.

The square root of 18857621 is about 4342.5362404936. The cubic root of 18857621 is about 266.1719590241.

The spelling of 18857621 in words is "eighteen million, eight hundred fifty-seven thousand, six hundred twenty-one".